Why is my video (thats not mine) on youtube blocked when others upload movies (not theirs) and they're fine?

I have all 4 seasons of the 90s show "Doug" before Disney got a hold of it and I'm trying to upload them to Youtube. Now, I don't own these, of course, but I see people do this all the time and they're fine. I see movies people upload and someone has uploaded all the Wizards of Waverly Place episodes and they're videos are fine. Is there a reason why I can't get away with it, I guess, lol?