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.

But, while YouTube is sometimes seen as synonymous with the Internet video revolution, there is a lot more to Web video. In fact, some of the most interesting video on the Web isn’t even the type of stuff that’s most popular on YouTube — short, one-off clips.

In various corners of the Web, people are producing real, episodic TV shows, including news, drama and comedy — sometimes with real actors and professional production values. Some of these longer-form, episodic shows are called video blogs, or vlogs, but others simply call themselves shows. Instead of lasting just a few minutes, they can run up to half an hour. These programs have more in common with regular broadcast and cable shows than with those emailed clips.

One of these days, a real hit show will emerge on the Web.

To be sure, such Web TV shows aren’t brand new. Ever since Apple began offering free video blogs on its iTunes store, people have been making them. One of the first to achieve popularity was a cheeky daily newscast called “Rocketboom,” which made a star of its first host, Amanda Congdon, who has moved to the ABC News Web site. (”Rocketboom” continues with another host.) Another was a comedy called “Tiki Bar TV.”

But the trend has accelerated and deepened lately, and a number of interesting sites have sprung up. My favorite is blip.tv, run by a team made up of a former systems administrator for the NHL, and a former TV news reporter and producer. Blip.tv (not to be confused with a similar-sounding site called bliptv.com) hosts a bunch of these new Web TV series, and also helps them attract funding, sponsors and advertisers. Anyone can upload a show.

One of my favorite shows available on blip.tv is called “Goodnight Burbank,” a comedy series about the squabbling that goes on behind the scenes at a local TV news show. Another is “Alive in Baghdad,” news reports from Americans and Iraqis on how the war affects average Iraqis. “Cube News 1″ is a series about life in the office cubicle. Other shows I’ve enjoyed on blip.tv include “HotRoast,” “The Ministry of Unknown Science” and “Josh Leo.”

Each show on blip.tv is accompanied by a profile page, comments from viewers and sometimes a blog. Many aren’t exclusive to the site. Some have their own Web sites, and episodes can also be found on YouTube and downloaded from iTunes and other sites. In fact, blip.tv provides links that make it easy to subscribe to shows on iTunes and other sites. But blip.tv does a good job of gathering a whole bunch of these Web TV series in one location.

Another good place to find these kinds of video blogs and Web TV series is at the iTunes Store. Unlike the music, commercial-TV shows and movies that Apple sells there, these Web video series are free. And because they are on iTunes, you can easily download them for viewing on a Windows or Macintosh computer, or on an iPod. You can even watch them on a real TV if you plug a computer or iPod into the set, or buy Apple’s forthcoming Apple TV product.

There are way too many Web series and video blogs on iTunes to list here, but if you go to the podcast page in the iTunes store and scroll down to Featured Video Podcasts, you can get an idea of what is available. iTunes includes several Web-only video series produced by the big TV networks, including a fascinating series from ABC called “The Day It Happened,” with historic footage on events such as the Kennedy assassination, the fall of the Berlin Wall and the wedding of Princess Diana.

Another site worth watching is brightcove.com, from a company whose main business is selling the technology for doing Web videos to big media concerns, including Dow Jones & Co., the publisher of this newspaper. But brightcove also hosts Web video from average folks and small outfits. It will soon introduce a feature to allow average users to record video directly to its Web site and then mix it, legally, with clips licensed from big media companies.

Yet another worthwhile site is Network2.tv, which attempts to aggregate a wide variety of Web videos in one place.

I’ve only scratched the surface of the available video sites, but if you like YouTube, you may love what else is out there.

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