I agree. The GW wants to play. The B&G is thinking about it, but decides not to.
Any time they are regurging for each other, it is a sign of affection, NOT aggression. So, no worries.
If they were actually fighting, if there was any real intention or aggression here, the greenwing would have immediately grabbed that foot and removed a toe... and trust me, if the B&G felt the least bit threatened, he wouldn't be sticking a foot out there exposed to the other bird's beak. It would have been feet protected stance, and sparring with the beaks... (Not to be confused with beak wrestling, which is macaw play.) Sparring is INTENSE, and bite pressure is used with the intent to intimidate. The next move is to twist the other bird's head sideways and go for the toes if the other bird does not back down... this is accompanied by unmistakable macaw "war cries." When you hear it, you will know, this ain't playin' and someone's gonna get hurt... (That's one of those sounds, that once you hear it, makes the hair on the back of your neck stand up!) With beak wrestling they don't clamp down. That's just macaw play time. And there is no "war cries." It's normal, and healthy.
There is also an entirely different body language to fighting, as opposed to beak wrestling. It is INTENSE... especially when you have to be the one to stick a body part in between those two. Incidentally, if you are ever in that situation (and I have been more than once) believe it or not, the best body part to use is the top of your head! If you stick your fingers in there, you may lose one! But there is nothing to latch onto on top of your head. So top of your head between the two beaks, swipe the arm, and put the aggressor on the floor. Then move them both back to their cages for a little time out... If there is an option to grab a towel and throw it over the aggressor, take it. If not use your head, and save your fingers...
Yep. Nothing like some smart person down at the rescue taking two large and dominant male macaws and setting them both down on the same playstand... (WHAT DID YOU THINK WAS GOING TO HAPPEN?! There can only be one dominant bird, and they're gonna find out which one it is. If neither bird is inclined to back down, you just created a situation... )
Anyway, that's how I learned this trick...