Dashcam - Appalling DPD Driver brake-checks and undertakes on Eastbound M27.

I observed driver on the eastbound M27 on the approach to the Hedge End junction, driving erratically and dangerously. They cut in beside me, in front of a truck carrying pallets, the driver of which they seemed to be having an altercation with. A moment after this, they moved into a short gap from the third lane into the second lane, forcing me to brake. I flashed my light at them to make them aware and the driver slammed his brakes on to try and brake-check me. Such was the ferocity of the braking, the van noticeably DIPPED.

They then pulled into the left-hand lane, heading towards the exit at Hedge End. I passed them and almost as soon as I'd got past, they swerved into the second lane directly behind me, tailgating me. They then put their full beam on, leaving it on for quite some time, blinding me. It was so bright, it lit up the vehicles in front of me.

They then moved back into the nearside lane and proceeded to undertake myself and other vehicles.