This would make the TV a killer set for me
Android TV does support screen recording through adb and it should be smooth enough.
FYI the Nvidia Shield Android TV devices have built in screen recording.
Just out of curiousity, what is it that you want to do with screen recording on Android TV?
I doubt it. I ran 3d mark on it, and got a 147. Switching between apps is sluggish. I would be shocked if it was powerful enough to record screen.