Sorry that happened to you. I couldn’t tell from the video, but it might very well be a driver I’ve had a problem with in the past (fat, white, middle-aged, if I recall correctly).
Me and my daughter were waiting for the 50 at the start/end of the route down Alki, along with a bunch of other people. The bus sits there with the doors locked until the driver is ready to start the route, me and the kid and a bunch of other people are obviously waiting–he never unlocks the doors, just starts driving away. Me and someone else knock on the door as the bus is pulling away, he glares at us, stops, opens the door, and then yells at everyone for “hitting” his bus! He angrily let everyone on, but never came close to admitting he was the one screwed up.
Anonyme is right, in addition to filing a complaint you should see if you can file a suit. I filed a complaint when it happened to us, but not sure it did any good…