What a moron. Glad there's no peds around at that time.
You know what I see from that video.
The camera rider and the other rider in yellow, riding too slow for the guy on the mountain bike. So he decides to pass, and the other 2 decide to be heroes up the pace to not let him pass easily.
It is obvious from the video that they both started to increase the pace once the mountain bike rider got beside them. Then wouldn't let him move in front. Their ego got in the way. All morons in that video.