Itunes Error Video Will Not Play Mac

I purchased a TV series on my PC. I copied all the movie files to my Mac and copied them to the video directory of itunes, when I try to play them I get an error that sais the song is not authorized on this computer. itunes will open and it will prompt for a user and password. ...

getting no audio on flash whenever I visit a website even though I get the video. When I try to open a windows media file i get a message that says THIS FILE MAY NOT PLAY CORRECTLY BECAUSE IT WAS COMPRESSED BY USING A CODEC THAT IS NOT SUPPORTED, then it will play with no audio. ...