I don’t have any info on why this guy is being beheaded but I can take a wild guess and say it’s due to drugs. He was already pretty beat up before the beheading started. The video doesn’t have sound through most of it, but you can hear one last huge gasp from the victim when his windpipe is severed. I’ve watched so many beheadings that I can’t even count, but the look on his face creeped me out more than I’ve been creeped out in a while. It almost looks like he felt it until the last second.
Thanks to @MrsPink.