No, "dressing in black" is not like a gender, racial, or sexual identity, and is not/should not be protected.
No, "wearing a mask" is a big deal, and if you don't want people to be intimidated by you wearing the mask, or making assumptions about the wearer, there better be some gas/smoke around.
Yes, smashing windows, using blunt instruments to destroy things, kicking fences, etc is "violent".
No, spray paint vandalism isn't violent. Yes, doing it will give a bad name to all protestors that you're intermingling with, and like the very right gentleman at about 7:55 in says:
"Not do dumbass shit that's gonna get everybody gassed and shot the fuck up."
These Black Bloc'ers are not everyday people just pushed to the edge...they are destructive and violent and provocating individuals, and would be so regardless of our society structure or government. Offer them no quarter, no excuse.