There are two models for this legal Internet distribution. Some shows and movies can be purchased or rented from services like Apple’s iTunes or Amazon’s Unbox. You pay a fee for these downloads, which don’t have commercials, and you can keep any videos you buy to watch repeatedly even without an Internet connection.

The other model, common on the Web sites of the TV networks, is free, ad-supported streaming directly within a Web browser. In this approach, you pay nothing, but you have to watch commercials that can’t be skipped. You must be connected to the Internet while watching, and you don’t get to keep the video.

This week, the ad-supported, streaming approach took a big leap forward with the launch of a Hollywood-backed service called Hulu, at hulu.com. Hulu aims to be a legal, one-stop shop for streaming of TV shows and movies from numerous networks and studios. It’s intended as an attractive antidote to pirate sites and to Google’s YouTube service, which has angered the media companies by allowing users to post all or parts of movies and TV shows without permission or payment.

Hulu is a joint effort of two big media conglomerates, NBC Universal and News Corp., each of which operates multiple networks and studios. (News Corp. also owns The Wall Street Journal and the Web sites where this column is published.) But Hulu contains programming from other companies as well, including Sony and Time Warner. All told, it offers full episodes or clips from about 400 TV series, plus 100 feature films.

I’ve been testing Hulu, and I am very impressed with its design and ease of use, and with the fact that it allows users to edit and re-publish its content on their own sites. Despite some drawbacks, it’s the first Web property I’ve seen from mainstream studios or networks that shows a real understanding of both modern Web design and the Internet’s culture of sharing. In my view, it’s far better than the typical network or studio Web site.

Even though Hulu lacks programming from ABC, CBS and many cable networks, it has a fair selection of popular shows, such as “30 Rock,” “The Office,” “The Simpsons,” “Battlestar Galactica” and “Saturday Night Live.” Its movie catalog includes old favorites like “The Usual Suspects,” “The Big Lebowski” and “Sideways.”

The site is organized in a clean, elegant manner. You can browse shows alphabetically, by genre or by network, or you can use an excellent search system. The search system even brings up links to videos of shows on other sites, such as ABC’s “Grey’s Anatomy,” that are missing from Hulu’s own collection.

Watching the material is a pleasure. You can view it in a fixed window or in full-screen view. You can also “pop out” the viewing window so you can place it anywhere on your screen and resize it to your liking. A feature called “lower lights” grays out everything on the computer screen but the video itself.

Even the advertising is relatively painless. TV shows contain just 25% of the commercial time that’s on regular TV. And Hulu allows you, in some cases, to choose the advertisers whose commercials you see, or else to opt to watch a movie trailer at the start of a video in exchange for seeing no further ads during that viewing.

In a break with Hollywood’s past rigidity, Hulu makes it easy to share, even edit, shows and clips. You can repost an entire video, or any portion of it, on your own blog or on social networking sites.

But Hulu also has some major downsides. Most important, Hulu lacks depth. Even with TV series from its owners’ own networks, Hulu typically contains only a small number of full-length episodes, and mainly offers short clips. In some cases, episodes expire after a while. For some shows, such as “Saturday Night Live,” there aren’t any full episodes, only clips. And the wildly popular “American Idol” isn’t in Hulu at all, even though it airs on News Corp.’s Fox network.

This stands in stark contrast to the depth offered on iTunes, where you can find multiple seasons of full episodes of many shows. And it doesn’t begin to compete with pirate sites, where you can find nearly everything.

Also, Hulu requires a decent broadband connection — a speed of at least 1 megabit per second is recommended, and even higher speeds are needed for some content. That means that using Hulu over the slowest DSL lines or cellphone modem cards will likely provide a poor experience.

Another problem is that, unlike iTunes or Amazon Unbox, Hulu can’t be used via a TV set-top box or a portable player. And shows can’t be saved for offline viewing, such as during flights.

Still, Hulu is a good start for Hollywood in finally providing a better experience for Internet streaming of TV and movies. If the service can add a lot more content and make viewing possible in more scenarios, it might strike a real blow against piracy.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

The issue: Viacom wants to get paid more than Google wants to pay it for all of those fuzzy, two-minute clips from programs like “The Daily Show” that users post to YouTube. The companies tried to negotiate a deal, but the talks failed, so Viacom is suing for $1 billion.

I am not a lawyer, and I have no idea how this lawsuit will wind up. I suspect it is mainly a bargaining tactic by Viacom. But I know one thing: This fight isn’t primarily about consumers and their rights, and its outcome won’t necessarily make things better for Internet users.

Consumers won’t be a party to this case any more than they were in the room when the latest major copyright law was passed by Congress. That law, the 1998 Digital Millennium Copyright Act, was enacted at the behest of record labels and movie studios. Their purpose was to stop people from using computers and the Internet to distribute digital copies of material to which they didn’t hold either the copyright or a distribution license.

That idea makes sense. Unlike some Internet zealots, I believe that intellectual property is real and that some form of copyright is appropriate to protect it. I am against the unlicensed copying of DVDs for sale on street corners, or the mass uploading of songs to so-called sharing sites.

The Internet and technology companies managed to insert a clause in the DMCA sparing them from penalties for carrying copyright content on grounds they were just innocent conduits. That will be a big issue in the Viacom case. But consumers got no such get-out-of-jail-free card.

In fact, the DMCA, and other recent laws and regulations passed under pressure from media companies, are pretty hostile when it comes to consumers. They turn essentially innocent actions into unlawful behavior, because they define copyright infringement too broadly. They have given rise to a technology called Digital Rights Management that causes too many hassles for honest people and discriminates against the new digital forms of distribution.

Even Apple CEO Steve Jobs, who created a DRM system for music that actually has worked, recently called for an end to copy protection of legally sold music, mainly because the record labels apply that protection only to online sales, not to physical compact discs.

Most honest people wouldn’t consider it piracy to buy a CD, copy it to a computer and email one of the song files to a spouse or friend. But the record industry, backed by the laws it essentially wrote, does. Most honest people wouldn’t think that uploading to YouTube a two-minute TV clip, which they paid their cable company to receive, is piracy. But Viacom, backed by the laws its industry essentially wrote, is demanding that Google remove all such clips.

To be fair, Viacom, unlike the misguided record labels, isn’t suing the actual consumers who posted these clips. It’s suing Google because it claims Google is making money from them and refusing to pay for that privilege.

Google isn’t blameless here, either. It does make money, at least indirectly, from other companies’ copyright material, for which it didn’t pay, even though it has negotiated some paid deals and says it is willing to negotiate others. And while Google says it diligently removes all copyright clips for which it hasn’t secured paid rights, every YouTube visitor knows that this system is, at best, imperfect.

As a nonlawyer, I think these clips seem like “fair use,” an old copyright concept that seems to have weakened under the advent of the new laws. Under fair use, as most nonlawyers have understood it, you could quote this sentence in another publication without permission, though you’d need the permission of the newspaper to reprint the entire column or a large part of it. A two-minute portion of a 30-minute TV show seems like the same thing to me.

But why should I have to guess about that? What consumers need is real clarity on the whole issue of what is or isn’t permissible use of the digital content they have legally obtained. And that can come only from Congress. Congress is the real villain here, for having failed to pass a modern copyright law that protects average consumers, not just big content companies.

We need a new digital copyright law that would draw a line between modest sharing of a few songs or video clips and the real piracy of mass distribution. We need a new law that would define fair use for the digital era and lay out clearly the rights of consumers who pay for digital content, as well as the rights and responsibilities of Internet companies.

If you don’t like all of the restrictions on the use of digital content, the solution isn’t to steal the stuff. A better course is to pressure Congress to pass a new copyright law, one that protects the little guy and the Internet itself.

Email me at mossberg@wsj.com. See video versions of my reviews at wsj.com/mossbergvideo.