The one against JMM was more of an overhand. Still, never noticed he uses that punch so well, most fighters dont even have it in their arsenal. Its like throwing a right hook from an orthodox stance, I never use to do it as you're never really taught it. Most coaches teach you to hook with your lead hand and straight with your back hand. It does expose you though which is probably which its not taught in most amateur gyms.
I actually think they're all overhands, but the JMM one is the clearest example, because he dips lower and really swings the left over. (The others do look like strange hooks too, though.) Either way, I agree that you don't often see it being used consistently on the top level. The last example I can think of is Maidana using overhand rights against Khan, and eventually almost knocking him down with it in the tenth round.