They threaten my life with their car, I threaten their life with a machete.
I've looked at the video several times and I'm not convinced the knifeman's attack is a result of the driver pulling out. (Although it suits the agenda of a number of media outlets to portray this as cyclist v motorist road rage.)
It looks to me like the knifeman has recognised the driver, the driver has clocked this and makes a desperate attempt to escape. The guy on the bike is already stopped (and I'm not referring to the part where the video is paused briefly) when the driver makes his abrupt exit which, frankly, looks desperate given the nose to tail queue ahead of him and the island at the traffic lights.
He wanted out of there in a hurry and it wouldn't surprise me if they knew each other, at least by sight.
Or I could be talking complete bollocks, of course.