Just pay attention in class and look at the overviews for the finals, and you will be fine. Also, the videos are actually entertaining... so unless you didn't sleep for a week, you won't fall asleep in his class.
Since this is a music class, the class should include a unit where the students use software to create their own music rather than the entire semester being about the history of music. This would be a great end of the semester assignment. Otherwise the class is fine.
If you have regular music appreciation rather than guitar app or music production you've frankly gotten the short end of the stick unless you are obsessed and know everything about romantic era music. It isn't an automatic 98+ class unlike guitar app and music production, however if you have Mr. Stephan and put the effort into memorizing the songs then you will do fine even if your test average is in the high 70's-low 80's