This was a Critical Mass event, which is why the bicyclists are taking up all of the street as a way to reclaim the streets and protest the lack of safety for riders under usual conditions. It’s not legal, but protests are never useful if they’re fully legal now, are they.
That’s awesome. I love that.
But that’s not the situation here, so already what you consider tolerable behavior and valid protest is law breaking in the context of the video. Surely you can see that reasonable people can also disagree on whether crossing the centre line is valid protest.