The problem is that while the driver is able to get all the way pointed backwards with regards to the corner, he doesn't actually enter the turn backwards. That makes it not a 'proper' reverse entry drift, if there you can really say there's a 'proper' anything in drifting.
This driver was at Ready Steady Drift at Pocono Raceway over the weekend. It's an amateur event, so there's no point in beating up on this guy for not executing a perfect slide.
Moreover, drifting is fun, don't take it so seriously, and enjoy this guy's either amazing stroke of luck or seriously outstanding car control.
This Is The Reverse-est Reverse Entry Drift I've Ever Seen