The background videos are mute so I added some birds at 0:00, an elevator sound at 0:05 (also for the hits in 0:18-0:23) and a rocket sound from 0:55
It still sounds kind of empty to me. What other freesounds would you add to complete the composition?
Maybe wind from 0:40 to 0:45? or a hydraulic machine sound from 0:47 to 0:50? any suggestion?
I'd like to hear a more intense rocket sound, it was too muted for the build up to that lift off, everything else was much louder than the rocket sound. Other than that I'm not sure why you think it seems empty? There's really no room for sound with the background music playing, the elevator sounds & video worked great together, thought it was an excellent job.