The video, filmed a few weeks ago, shows the sailors singing an Indonesian hit called Sampai Jumpa (see you later).
Officials confirmed on Sunday that the KRI Nanggala - which sank off the coast of Bali on Wednesday - had been found split into three pieces on the sea bed.
All 53 crew were confirmed as dead.
The submarine had been taking part in a torpedo drill just before it disappeared and the reason for its sinking is not yet clear.
The video shows the vessel's commander, Heri Oktavian, among those gathered around a crew member playing an acoustic guitar.