The video features closeups of what appear to be an anatomy skull of an animal.
The description of the video was:
The word "grouse" means a medium to large game bird with a plump body and feathered legs, the male being larger and more brightly colored than the female. The Japanese characters translate to "recurrence" in English.
The video resembles a Sewnkin video titled "sewn kin 2" but it's filmed from different angles and is in higher resolution than any known copy of "sewn kin 2". This is most likely why Meatsleep chose characters that translate to "recurrence".
The skull in the video has been identified as that of a horse.