He saw it was 1 dedge solved, so he did 3-2-2 edge pairing. I suppose you could define what type of edge pairing someone is doing by how many edges they solve between when they first slice and when they finally slice back. As you'll note in the reconstruction that he placed the GO edge piece after the slice move so that it *would be solved when centers are finally re-aligned*, but noticing that the RB pieces were ready to be paired as well in those inner slice layers, he formed it with 'u d' (not messing with the positions of the to GO edges), and then noticed what the solved RB dedge needed to be swapped with (the other YG edge) so that when centers are realigned, it would form the YG (and first GO) dedges at the same time. That's the tricky 3 edge part. The remaining 2-2 are pretty standard