It’s really George, but the guy who looks like David Gilmour is actually famous Russian character actor Igor Kuznetsov. George’s cousin was hired to make a novacane commercial for Russian TV, and George’s reviews gave him the idea to stage that scene to the accompaniment of a Russian-language cover of Comfortably Numb. George agreed to participate.

Gilmour was not amused. You’ll notice that he’s played zero concerts in Russia since Floyd in 1989:

https://www.setlist.fm/stats/david-gilmour-7bd6ba00.html

https://www.setlist.fm/stats/concert-map/pink-floyd-13d6adc5.html