Each composition is in the public domain, yet YouTube has flagged my account with a copyright infringement warning each and every time.
Because somebody else recorded a Schubert Impromptu,for example, YouTube's Content Management System assumes I uploaded a copy of a recording owned by one of the major labels. I have to respond and inform them it's my performance and it is a phonorecord I own.
It makes sense to have all your permissions in order. There is a lot of new music I want to include in videos. That requires something called a synchronization license. They're easy to get and I recommend you get them so that if (when) your YouTube account gets flagged, you can document your authorization for the video and prevent closure of your YouTube account.