Cars with dashcams installed - owners being idiots!

[W4NTED]

SO was on the M1 today and a nice empty stretch of road ahead. A BMW 1 series was hogging the right hand lane doing probably 65mph and I approached from behind at speed (73mph). As he had no ideas to move I gave him a little flash of my headlights. To which he responded by slamming on the brakes and then pointing towards his dashcam!!! He was basically trying to say "Don't mess you are being recorded"

First of all the hogs a lane and then won't move but is acting cocky as he has a camera - I mean W T F!

He just did not want to move out of my way and wanted me to over take him from the left.

I'm getting ready for being flamed by the PH crew but who was wrong here me or him?