Many companies have figured this out and begun acquiring tech outfits even before they have a business model.
The most notorious such acquisition was Google's purchase of YouTube. And now, over a year later, they claim to have that business model problem licked.
The answer -- overlays. Clickable ads run on a portion of the screen, for a portion of the clip's run-time. The alternative, running ads before, during or after the clip, was rejected by Google because, it said, users wouldn't stand for it.