"You get 4 downloads"
Why limit it? It seems totally against the point. Why not even let people download a torrent and they can get the video on as many devices as they please and it wont even stress his servers.
Limiting number of downloads protects their bandwidth from would be jerks. Protecting their service is important for their customers to have a quality experience. It's fair, and most people will only ever download once. If they for some reason use up all 4 downloads and want more they should e-mail them. Why wouldn't give more if some had a genuinely good reason for using up their downloads?