I have videos on iTunes that I've purchased that I'd like to watch on my big screen TV. I'm wondering if there's a way I can send them to the XBox?
I also have PlayOn but I'm not sure if/how to do it through that.
You can't, as the Xbox doesn't work with FairPlay, the protection system that iTunes uses. You can't view them outside of Quicktime and iTunes. You'll have to buy, or "buy" it again.