[Baldie]

I think you are most likely looking for a looping video bottom right of UI while casting. See this for an example.

http://www.twitch.tv/baldie24/c/1805342

It uses a cutout of the UI to put over the video so it doesn't overflow. You could then put anything you want from sponsor logos, casting information, next event details etc.

Is that something you would look into or do you want a specific in game overlay.

If you want a video loop I'll be able to knock one up quickly and teach you how to use it effectively.

If you want an in game overlay I'm happy for Flamga to do it as he has had a lot more experience in making them as I have never really liked using them!