The beginnings of a quiet battle between online video providers and traditional broadcasters for sports rights are appearing. Live sports represents that last stronghold that traditional TV players have over the army of new entrants, but the digital players are beginning to edge in on that territory. The shake-up will be interesting to watch, as digital video providers are using sports assets in a completely different way from how broadcasters have traditionally used them. Amazon is the best example of just how different motivations are between the incumbents and the new entrants: Amazon paid some $50 million for non-exclusive rights to stream 11 Thursday night football (TNF) games this season. While that $50 million is 10 times what Twitter paid…