Hello and welcome to the forum.
I've removed the video link from your post as you mention that it's not your video and the owner may not want it shared
I have watched it and the hamsters are Syrian hamsters, but I would say that there are a lot of them in that cage, even for a pet shop. I would suggest you visit the shop, and ideally other pet shops local to you, before buying a hamster to assess the conditions the hamsters are kept in and how well they look. I appreciate it may not be easy to find pet hamsters in India but if you can look at several places and choose the one with the best conditions then it may save you the heartache of getting an ill hamster. Also, I would suggest you give any hamster a health check before buying it and taking it home. Some suggestions on how to do this can be found
here and
here.
Good luck in your search for a new pet.