Seems like you should use CloudFront for things that are both small and need to be fast (HTML/ JS/ CSS), and then use a separate service for hosting your fat media files. Heck, rent a pair of servers with unlimited bandwith somewhere for $100 a month. Yes the bandwidth may be a bit oversold and spikey, but if a giant file download slows from 10 MB/ sec to 5 MB/sec for a bit, I doubt it matters THAT much.