I think you'll find that the copyright Laws are a little more strict, but also more fluid than you guys all think.
For a start, the term was extended thanks to your friend and mine, Bono of U2 fame. The term is now 70 years and the clock doesn't start UNTIL the original owner is dead. It's even called 'The Bono Clause'.
And furthermore, just because the composition is from the 1800's doesn't mean it's not still covered. This is because the recording itself has copyright too. So the music could be from 600 BC, but if somebody recorded it yesterday, they have a fresh copyright for the recording and you can't use it without their permission.
I used the UK National Anthem 'God Save The Queen' at the end of my London tour video. Sure enough YT flagged it because it's a recording by the London Philharmonic from the 60's or something.
One way to get around this, if you can, is to create your own version of the music. I put together a little guitar only version of the national anthem, re-uploaded the video and VIOLA! No problems! I can even monetise it and keep all the cash. I'm practically swimming in money because of it.....
Oh and that doesn't mean just remix it. Samples are covered under a WHOLE other nightmarish stack of rules! You have to create and perform everything yourself.
The music is right at the end...