If you use the Banshee Daily PPA you may have recently noticed* a new entry in the left hand menu panel: Internet Archive.
Through this you can browse all sorts of royalty free and public domain works – including live performances, concerts, movies and books.
Sadly for me Banshee insisted on crashing whenever i tried to watch a film so i can’t demonstrate it as it should be, but i did manage to stream a (randomly clicked) video as flash.
Videos can be viewed as various options (depending on the video in question) such as flash, ogg, mpg4, etc.
Everything is done -in- browser so you can search, find, download/stream and watch all from the one interface.
Audio, just like movies, can be streamed in a variety of different formats.
*Disclaimer: I’ve not used Banshee for a day or two so i’m not sure when this feature landed.