Users have already been making money for years through the site's YouTube Partnership Program, which shares ad revenue with members, many of whom are popular enough to make a living uploading videos on a weekly basis. More recently, "one-hit wonders" have also been able to reap rewards via the Individual Video Partnerships, so suddenly hot viral clips like "David at the Dentist" can garner submitters financial gain in addition to their 15 minutes of fame. But most of these moneymakers are short subject videos and feature-length submissions may not be as successful, either with ad share or rental models.
The great thing about Netflix Watch Instantly is that a low one-time subscription fee gets you an unlimited amount of movies. You can easily give any film a chance and not feel bad about disliking it or turning it off after a few minutes. Per-film rental prices are more of a gamble. I wouldn't have watched Triangle on Netflix last night, for example, if I had to consciously put down a few bucks and worry that I wouldn't like it. Maybe if a filmmaker with a large fanbase debuted his film as a YouTube rental it could be profitable. And it might work for those studios who've put their films on the site. But I don't see a lot of unknowns gaining as much exposure with this kind of platform.
One thing that might make it more appealing to viewers, though, is YouTube's new partnership with Verizon FiOS, through which customers will be able to watch YouTube through their cable box. Additionally, for users who've previously had problems making money due to their videos featuring copyrighted music, YouTube is working on another new program to allow users to purchase music licensing rights. Hopefully at a cheaper cost than normal.