Fuzzy area that the courts are beginning to work through. Obviously you can't take an ESPN broadcast and use major parts for recreation purposes, but with one's own recording this situation is less clear. Generally the question is whether the event holder wants to stridently pursue actions against an outside source, and obviously the NFL, NBA, and other pro sports would sue about an outside transmission of their games. But if the event holder sees an advantage to letting an outside source promote their games and generally does not see a way of getting revenue from it, it's easier to let it be or work out a mutually beneficial agreement with the outside source. The music industry learned the hard way the disadvantages of taking the storm trooper approach, and in today's world it's very hard to enforce anti-videoing rules even if eventually the courts for some reason uphold very strict copyright interpretations. Besides, after the stink about the NASCAR accident video, there is going to some push back against sports organization trying to control all information about their events.