Facebook – How to Disable Video Auto-Play

I believe Google has disabled the keyboard shortcut for muting a video call using the spacebar, so I don't believe this is going to be too much of a problem now.

I can suggest, however, is to lock the keyboard if you are on the video call, which prevents toddlers from accidentally pressing on any keyboard buttons while on the video call, but you can try other ways of preventing the toddler from messing around with the keyboard though.

Yes, you can. Go to https://www.facebook.com/settings?tab=videos.

The page should say Video settings, and an option on the right to disable auto-playing. I just tried it and videos do not start automatically anymore while scrolling.