My initial impression was that he tilted the bike too far and grounded something that doesn't move, lifting the rear. Been there, done that. I personally enjoy it, but I guess you gotta know when it's coming to enjoy it, huh?
The old addage of "when in doubt, gas it" is somewhat valid, depending on circumstance...front or rear?
For a front end slide it is almost always valid, as most front end slides are the result of a front that's overloaded. During overload a judicious application of throttle lightens the front and regains traction. In nearly 30 years of riding motorcycles I can count on one hand (OK....one finger) the number of times I've lost the front because it was light! (and that one occurred in a right hander on a hill that crests during the turn....it's turn two at Barber Motorsports Park....and it resulted in an unrecoverable slide because I wicked, lightening it further......oops.......I still wick when the front moves....experience still says its the correct action)
For a rear slide it depends on severity. Typically I'll simply maintain throttle rather than wicking. If the slide is "new" and the yaw angle is minor, this, or a slight increase of throttle setting, actually results in optimal acceleration off corner. If, on acceleration from corner exit, the slide is minor and grip suddenly fails, but yaw is still minor I
chop throttle. I didn't say decrease, I said "chop". While the yaw angle is minor, a sudden reclaimation of grip and the accompanying directional correction are easily acceptable. I've never crashed with this technique (until it happens this coming Sunday since I haven't knocked on wood). If the slide is well developed I maintain throttle and steer in (countersteering, more kinda dirt track style). Nearly as often as not, in my experience, this results in a low side....but having tried the alternative I'll slide, please. I've rarely gotten to this point on the street, as my feel for the rear is such that I avoid slides of this magnitude on asphalt. Modern rubber typically "goes off" slowly and predictably with a few exceptions.....like early Pilot Sports and a few Dunlop offerings I've tried that hold until they don't, new or old.
To me, this rider would have been better served moving his weight to the inside of the turn, decreasing the lean angle required to hold the turn at his speed. This is why "hanging off" works! If you're grinding hard parts, you need to either move the hard parts up or, in the words of Jamie James at the Schawntz School, "Get your ass off the bike"...as he told my buddy Chuck Campbell to get him to hang off more.
The MSF school assumes you're riding a 700 pound HD and you're sliding because you're on ice or you've locked the rear in a panic slide. The MSF is a GREAT tool for beginning riders, but it's not a handling school!