To answer a few things:
In the UK, it is illegal to cycle on the pavement (sidewalk). However, this is generaly waived when dealing with under-16s.
In the UK it is legal to "lane split", this is where you can have a bike cycle up beside your car and still be in the same lane. However (something that is often missed) is you should only over take to the right, you shouldn't "undertake" as it is often called, unless the vehicle you are beside is turning right.
There is nothing to indicate the cyclist made any gestures towards the driver. Modern buses in the UK tend to have a host of cameras in and on them, generally covering the passangers inside (from a number of angles, where you could typically see some of what happens to the sides of the bus, as well as cameras infront and behind the bus. This is not true of all buses, but that one seems to be fairly new, so I'd suspect it would have cameras. In which case, they would have likely be used in evidence.
Just because there is a queue of traffic, does not mean the cyclist is at fault, there are two lanes there, I see no reason why drivers couldn't overtake prior to the junction (where you'll note that one lane is for a turn off, the other is straight on).
I've seen behaviour like this from some bus and taxi drivers before, they get ****** off because there is someone slow infront of them and I've seen them trying to intimidate cyclists by swerving infront of them and passing so close they practically knock them off their bikes. Heck, a friend of mine was taken off his bike just a fortnight ago by a taxi which proceeded to speed on without stopping.
Regardless, even if the cyclist wasn't being a douche, there was no excuse for the driver to act that way. By the way some of the posts have gone in this thread, it sounds like you'd shoot someone simply for cutting you off
