It works, but it burns through so much CPU your computer will be a gibbering mess. There's some pretty silly inefficiencies going on, for example; if you switch away to another window, they display a small video player while keeping the big one running the background. Each time you switch into screen sharing mode, they drag you back to the app again. If you draw on the screen, someone has screwed up their linear algebra so you end up seeing double with an extra copy of what you're drawing, in totally the wrong place.

Annoyingly it's a bit too convenient, so going out of band is a pain.