The egg thrower and her pals are likely members of RevCom, the Revolutionary Communist Party. That’s an actual group active in SoCal and they routinely are violent. This was mild.
It’s hard to say, but the black guy at the end of the video with the blue bandana and mirrored sunglasses looks like an SEIU organizer who has been active this year.
Could be RevCom as well. They are not mutually exclusive.
Yes, theoretically it could have been a rock which this leftist had been hurling - but it is still beyond rude towards Mr. Elder...
Well, one thing the left has never had is class; at least not in my lifetime ;-)