Video Format

I've been trying to add a short video to show when the broadcast is going to a replay, however I can't seem to get the video to play smoothly. It always seems to be blank for a moment, jump to near the middle of the video, and then play the rest normally. Is there a particular video format that works best?
I've currently got it encoded as a .mp4, but I've tried .wmv and .mov. Mp4 is the only one I can get to display in ATVO, but as I've said, it's choppy.

What's the size of the video? It should be preloaded but maybe something is going wrong and it takes a while to load...

Let's resurrect an old thread: I've been recently revisiting this issue since I've been building out a new theme. The issue I'm running into now is that the video plays, but the screen remains black at the end of the video. The only way to resolve it is to close the theme. My video is a 244kb wmv file at 1280x720 resolution.

I have read about some issues with black screens and videos and I think it was related to using multiple monitors (perhaps at different resolutions or some other configuration that made it now work).

Do you use multiple monitors (I'm guessing yes for streaming)? And if so, can you reproduce the problem often? Can you check what happens if you put the overlay on the other monitor instead? And what about disabling all other monitors and trying it on a single monitor?

Yes, I have multiple monitors, they have different resolutions. I can't find any reliable way to make the black screen happen, it worked fine when I first implemented it yesterday morning, but by the evening it was going to a black screen every time. I can try it with a single monitor, but I can't work that way, so if it'll help troubleshooting I can try...