I agree, it would be wonderful to find video of my ancestors that others have posted. I have just started making short clips from old 8mm movie films. Sadly I have to post them to YouTube and then put the link on my ancestry page . . . and that isn't clickable. I have film of my grandparents and even one set of great grandparents from the 1930s.
I have read that it is possible to get webcam emulator software for the PC that tricks Ancestry into accepting video clips because it thinks they are coming from a webcam. Sadly this does not seem to be available for Apple Mac computers.