I think I found her.

Alright, this was what happend to me and for so many other who watch the live stream. After the intro we saw Rainbow fixing a banner. She then dodges a lightning bolt. But just as she mentions "Derpy" the stream dies. Everyone went crazy, it was horrible. we all missed her speaking lines and it came back after Applejack was done with the motivational speech. My guess is that the host of the stream choked on the awesomeness and accidently turned it of in shock when he heard her name,