"Deeper Underground" is a single by British funk and acid jazz band Jamiroquai from the soundtrack to the 1998 film Godzilla.
This song was one of the last to feature founding bassist Stuart Zender, before his departure during the recording of Synkronized.
The theatre turns into chaos as the audience tries to get out alive, in the midst of which Jay Kay appears and sings and dances on top of the seats.
At the end of the video, the camera pans out, and it emerges that this entire flood was itself being watched by a different cinema audience on another screen.
[1] Another version of the video replaces Godzilla with a man in the movie who smashes an aquarium, causing the theatre to flood.