I wouldn't be too sure of the specific name 'technique' that is involved (I could be incorrect), but he is putting different ways of technique into this performance. He seems to be alternating in the right and left hand, the right hand as the melody, the left hand as the harmony to accompany it. He switches the left hand note every so often (more or less, every phrase) to fit what the RH hand is playing. Then, as you progress in the video, he is playing triads major/minor in the left and notes (probably 5ths, 7ths, 9ths, root, etc) in the right hand to make a chord. He would play the three notes in the triad in the left, then ending it with a top note in the right. Then, he begins to rush, purposely or not. If I would say the technique that is used in this would mainly be:
1. keeping the RH melody (balance, in this case)
2. staying in tempo
3. prevention from 'banging' the LH notes
4. careful attention to the fingering (there appears to be several phrases where it is questionable, but I will look into it further)
5. making the broken chord phrases smooth, as if they were together on one hand
If this combination of technique has a certain name, I would research into it to find out more.
Cheers!
magic_sonata
Topic: technical doubt