Thanks for sharing the video!!
The Russian implementation is quite comfortable, but it only has a capacity of 64 passengers. A sleeper accommodation in DD coaches with higher capacity than a 3A coach is quite a challenge ( and necessary for DD to be chosed over 3rd A/C).
RDSO had conducted some studies on enhancing the carrying capacity on IR's coaches. They evaluated several options based on the feedback people had given on the side middle berths introduced a few...
more... years ago. The primary problem people had with them was claustrophobia. For the same reason, RDSO felt that adding sleeper accommodation to DD coaches would result in the same response from people.
They concluded that increasing capacity would require a change in the permitted dimensions of the coaches, which would need some modifications throughout the routes they run on. ( Not major modifications though). Many zones have had problems with changing the coach dimensions as the sections of track capable of handling the modified coaches are fragmented and most of the route has to be upgraded.
They evaluated options to increase the capacity in 3 tier coaches to accommodate 4+4+3 passengers per coupe, by modifying the coaches to allow an additional 2 feet headroom inside. These discussions were published last year and they still seem to be in a R&D phase. For now, it seems very likely that the Uday coaches will end up with a chair car configuration only.