It happens from time to time, but I noticed that the video playback is much more consistent now than earlier in the season. Due to the high volume of people playing this game, I'm sure that it's something that they've addressed, and are working on.
Yep. I've actually asked Glu about the requirements a few times, and they don't actually reveal the exact parameters. My advice is just to keep being active, and if it happens then it happens.