I don't get why you got so close to the BMW X5 the second time round. If somebody's driving like a nob (and that driver clearly is), you really should keep your distance, not attempt to overtake, and clearly not considering you cut in front earlier after he tried to brake-test you.
The Highway Code clearly states that you should not allow other drivers affect the way you drive (I.e. According to the rules) but it's clear with the Peugeot at the start of the clip.you ease off the gas to hold him up when he tailgate you. Then you put your foot down when he changes lane. You then put your foot down again when he overtakes the estate car. At this point you yourself are speeding in the 50 Zone. Your intention was clearly to try to block his way back in to your lane. You failed. He drove like a nob. You drive like a mob and was probably lane hogging to boot.
Who took the photo , why post on Facebook