That swerve alongside the bus is probably the most interesting maneuver. The roadie had just previously swerved out into traffic enough for the BMX rider to go around the bus. The maneuver is last second but it creates room. Then he swerves right next to the bus and eliminates that room.
Who wants to bet the BMXer took that narrow space between the roadie and the bus when it opened and then got seriously cut off when the roadie swerved?
That's not saying that the BMXer was in the right. **** him. But it's easy to see how he could feel screwed with and retaliate. If you don't want retaliation from other road users don't give them things to retaliate against, right or wrong.
And I'll say it again. If road bike guy had ridden his pedals more than his brakes none of this would've happened. There's no good reason BMXer should be able to keep up in the first place.