This is an unusual entry into Bollywood Tuesday, as it was never part of a film (as far as I know). However, it became popular primarly because it starred Amitabh Bachchan (the thinner man in the video).
Amitabh Bachchan is a Bollywood Legend. He is considered a national treasure. Back in the Eighties, he became very sick and literally MILLIONS of Indian people prayed for his recovery. Read the Wikipedia page that I have connected to this post to see just how popular and beloved he is.