When I published the first part of my Apollo 8 flight, I got a copyright warning.
How can I defend, now, that I didn´t use copyrighted sound?
It's quite common to have copyright claims (claiming revenue share), but usually the video remains playable.
I've had this problem with a few things:
» Apollo 11's Armstrong transmissions. Someone has put them into a "music".
» Magellan Venus animation - used on a crappy music video
» John Glenn's audio - this came out on old 1960's LP records with some orchestra music
» Voyager Jupiter encounter animation - BBC claims this because they used it on documentaries.
Even so I never had a copyright strike. Only blocked videos on certain countries or revenue share claims....
The best solution is to replace the problematic segment. Also check the muting option on YouTube - sometimes it's able to remove just the offending music.
But be warned that it might happen again. I've had YouTube's own library music being claimed after a few years.
The key is to prepare for that and have a good workflow that allows you to render a new video quickly.