Yeah, my MMA coach taught me that one too! The one that you're talking about, that is. With the exception that we used to trap the other guy's right arm in to the armpit of our left, then wrap our right arm around the guy's neck and then drop/jump to the side of the guy. Feels like your head is gonna pop off like the cork of a champagne bottle.
I was taught what that sounds like by John Will, and he specifcaly said it was a wrestling arm spin not the judo style throw when he taught us. I find it great for ending up in really strong position on the ground as well as people (so far) not really expecting it as a set up.
The difference between an over rotated shoulder throw and an arm spin is whether your opponent's arm is wrapped around your shoulders or your neck. You can see a great example of an arm spin done here during the wrestling worlds:
Originally Posted by Pakeha
That would still be taught in judo (as Yoko Wakare). While neither an over rotated shoulder throw nor an arm spin have a great risk of sacrificing the back, the placement of the opponent's arm can change the nature of the throw significantly. Unlike an arm spin, an over rotated shoulder throw can be executed without a drop (if you're willing to sacrifice the longevity of your lower back muscles, in my experience).