I have 6 PS EYEs which can be recorded normally on iPi Recorder.
I also have an Xtion that can record normally but has a Broadcast button on the Record page to live to iPi Mocap Studio.
But ps eye doesn't have that button to live.
Is it something that RGB cameras can't do?
Can I only record and then import it into Mocap Studio?

Indeed, this feature is only supported for depth sensors.
This is not stated well enough in the docs though. We'll improved that.