I've gotten dozens of reports about this and all I can say is that it's most definitely on Firefox's side. I had a user send in a bug report and the best we can hope for is for them to fix it on their end. Standalone or Chrome should work fine.
It's strange, because I only use Firefox and have never been able to reproduce this bug, and meanwhile, I've had other people stream the game to me and have a 100% reproduction rate. It consistently doesn't happen on Chrome, either.
