EDIT: Thank you all for detailing your experience with, and hatred for, this miserable product. Your display of solidarity is inspiring. Now, say it with me:
The fact that me and a coworker can't both share our screens at the same time is absolutely batshit. 1x1 collaboration isn't even reasonable, nevermind anything more
Videos can work, but I think you need to enable some feature that prevents tearing. It works fine for people who frequently present with it, but I honestly just avoid videos in my presentations because I don't want to mess with it.
Honestly, I like that it doesn't have it. We use Teams for meetings where one person is presenting, and if someone else wants to share, then we're going to switch presenters. Making sure everyone sees the same thing is important.
We use Slack for 1:1 or other impromptu small group discussions, and it supports multiple people sharing their screens.
So for us:
Teams - larger group meetings with generally one presenter; collaboration happens via audio, not screen sharing
Slack - smaller group meetings where there's a lot more active collaboration with screen sharing and whatnot
I only use Teams for scheduled meetings and Slack for everything else.