Youtube is a very powerful way to get your users. And if you are smart enough to make your video very appealing, many people will embed it, and it will propagate on its own. I've seen some of my videos on myspace profiles, university pages, etc.
For example, like what I did, I did a movie of 500-600 pictures of Budapest, and of course I made sure that the central pictures are from the "Budapest Parade" section =)))
Example:
Here