The NFL deal is also a good example of the care Twitter and its TV partners need to take to make sure video on the service doesn’t cannibalize existing businesses.
For instance, the NFL will only send out in-game highlight clips during the Thursday night games that it carries on its own NFL Network. On Sundays and on Monday nights, when Fox, NBC and ESPN have the rights to the games, it will wait until they’re over before it sends out clips.

Twitter Snags the NFL for Another Ad Win - Peter Kafka - Media - AllThingsD