That's so fucking stupid and it pisses me off that the NFL does that. Meanwhile the NHL has their own YouTube channel, and they practically encourage fans to make highlight videos. LA Kings (who also have their own YouTube channel, as do many other teams) would link fan made highlight videos that were good.
NFL is incredibly greedy, I don't know what their motivation is for doing this, but they can't be making enough money to make it worth it. Instead they just look like a bunch of fucking douchebags.