I am in the process of building a flex based video sharing app which does exactly this... including moving the files to amazon's S3. the demo is at http://demo.rohanpinto.com. I shall be releasing the entire app as opensource code and make it available for download soon.
the difference with this app and the approach you have mentioned is that I use HTTPService to procure the videos and SWFObject to display the video..
I also have included a youtiube video indexing scripe which allows for indexing / bookmarking all youtube videos too...
I bet there would be tons of video sharing apps in flex that would pop up, but this "open source" app I promise would be the "best"... as all i concentrate on is the functionality and not the look and feel, I shall "seek" help from other flex developers to build themes an have runtime CSS's that can be imported into the app...
BTW: I'm a flex newbie and have gotten from learning flex from ground zero to developing the app as it stands in the demo page in less than 7 days (ah !... not to forget the time i spent on my day-job in those 7 days)