Copyright?

So I'm kind of psychotic about if I'm going to get angry messages from people when I post a picture or something or mention a book or post a video or anything else in that matter. Why? Copyright that's why. It confuses me so much and I'm not really sure what I'm allowed to do or say and what I'm not.

Because of these issues I thought I would share this video with you that pretty much explains my feelings on this matter.

Yes. That is how I feel and yes that was Darren Criss who is now Blaine in Glee. Now then this video is by Starkid who I have recently become obsessed with. They had Darren Criss before Glee and they have done some amazing stuff that is awesome and funny. Will you be hearing more about them? Probably.
~Scooby

P.S. So maybe my situation isn't quite the same as there's was. They took their stuff down because they did a musical on Harry Potter and had to make sure there weren't any copyright issues. They got so much attention which is why they got worried. Yeah I'm not taking this down and I'm not nearly that popular (I'm pretty sure the only people that read this are people I know).