it's difficult to say given that there are no indications as to what speed these drivers are driving on this 2 lane road, but if i were the BMW driver :
1. I would not have jumped in in front of the mazda unless i was pretty sure i wouldn't impede his progress.
2. if i did, I would have been reasonably sure i could "dance" thru these paths with mazda at the boundary of speed limit. i wouldn't go much faster, and if mazda was maintaining his distance, i would have been perfectly happy.
BUT at least we know the BMW driver was watching his rear view mirror. there are so many drivers that never pay any attention to the rear view mirrors...
with regards to road rage in general, i try not to be an a*hole. i don't think i ever "brake check"ed anybody, even though some try awful hard riding my rear when i'm stuck behind someone on highway blocking the left lane.