What does the highly esteemed Criterion Collection, distributor of film buff collectors’ editions, do in a digital age? Very few of its chosen “important classic and contemporary films” are available in any online format. If you want to buy a movie online, chances are it’s going to be Zoolander on iTunes. But Criterion this week started offering its own digital videos on its own web site (there’s a cute Sharpie-drawn introductory video on the main page, but it’s not embeddable).

We gave the “online cinematheque” streaming system a whirl on this quiet Friday. Here’s the deal: Movie rentals cost $5. You can stream them as many times as you want for a week. Then that $5 counts towards the purchase of a DVD. Today there are only 20 films to choose from, but apparently more will be posted each week.

The process is simple and works well — pick what you want, enter your credit card, and wait for it to load (which in my case, freaked out my browser a little bit both times I tried it, though not for too long). Film delivery is powered by BitGravity, and it’s restricted to the U.S. and Canada. The quality isn’t crazy amazing, though that may be due in part to me picking an older film. However, I would say the interface is almost too simple — it’s just a video with the option to turn up the volume or go full screen (see screenshot above). There’s no info displayed about a movie while you are playing it, and you have to buy the DVD (or Blu-ray, starting next month) to get the special features (boo!).

Criterion is also offering, in partnership with new film social network The Auteurs, a free ad-supported online film festival once a month. This is poorly presented, because some of the very same films you can get for $5 at Criterion are free if you click through a different part of the site to The Auteurs. And if you click to play on the Auteurs, the movies are presented in the exact same BitGravity-powered streaming player (but preceded by an IFC film preview pre-roll ad). Do you really want your first customers banging on your door asking for a refund?

Either way, it’s good to see more and better movies coming online. Between startups like Jaman and Hulu, expanding outlets like Netflix and iTunes, and now even YouTube getting into the act, the online movie theater is finally opening for business.