It is really bad at the moment. Large companies dealing copyright strikes right, left and centre, claiming videos with music in the background, covers of music, people teaching songs, even videos that had artists names in hashtags, etc.
But it also affects videos that use short snippets of TV shows, movies, programmes for illustration, getting copyright strikes from large sources - sometimes under completely false pretences - a friend of mine just regained control over his modern history themed videos after Chinese TV channel claimed the famous CNN footage of a guy stopping tanks on the way to Tiennanmen Square belonged and was copyrighted by them, they took over income and control of his 20 minute videos that used about 15 second snippets of the famous cam video. It took him like six month to battle them down and during that time they made his videos unavailable in various countries and on all mobile platforms. Large corporations and TV stations are really predatory on youtube at the moment.