I assume he's asking about 3rd party software, which may be more limited than what Apple's built in software is allowed to do.
That's correct. I updated my comment.
By the way, someone else commented further down that Apple doesn't allow third party apps to use it for realtime (video chat). But I can't verify if that's true or not.
Apple doesn't facilitate realtime use through AVFoundation, but there are workarounds. Apple doesn't specifically restrict realtime use and does approve apps using the workarounds.