It's good to ask those things. I can only answer for myself, which is maybe not a western view point, but anyway:
I assume almost everybody thinks shining lasers on the old lady is bad. I don't think violence against civilians is ever justified. However wrong though, it is probably never fully one-sided
The last video you linked ends with a 'civilian' having molotov cocktails thrown at him, and the author of the video uses this to discredit the protests..... But... that 'civilian' has a gun in his hand. He is an undercover officer, and those events happened shortly after police shot someone with a live round in the same area
The police have not pressed charges against mafia caught on camera beating people up, but they have recently arrested a pregnant woman for wearing a facemask*
I think the protesters have been more restrained, but they still definitely make mistakes. Sadly this doesn't get us out of the spiral of violence: to do that the gov and police would have to face loosing their jobs; and maybe just as hard is they would have to accept that the protesters' anger and vitriol as true
--
Nonviolent means were employed during the earlier umbrella revolution and occupy central. These didn't seem to work. But I agree that the anger, vitriol, and violence on all sides is creating another wall...
*facemasks are quite different in HK than the west. The SARS epidemic and close living quarters means people see them as essential to health and safety -- so the facemask ban is bordering on offensive in HK culture
-- Hope that helps. Years ago I was in a warzone where the people were undefended by their government. The church was preaching forgiveness to those who attacked them, and it was impressive to see how effective it was. But it was a very big cost