From a television screen, you get to see what a monitor shows you. Sometimes you can see where a horse is not going to perform like in the past - crazy in paddock, no warm up, jockey walking horse without feet in stirrups, bucking jockey.... or a first timer has exceptional size and muscling, feeling good
I think there were 3 videos from Takach and Ledbetter and another couple books.
Here is an interesting article...
http://www.drf.com/news/eye-beholder-what-look-race