I use iSwifter and it's not download capable. All it does is allow you to access the iSwifter developer server(s) which allow them to feed/stream you Flash video, or play some Flash games.
Its a browser that only streams. I do use it when I run across a Flash video that I can't view in Safari and, so far (knock on wood), I've been able to view all the videos that I've tried.
Hope this clarifies.
Marilyn