Q: need help, constant repetition of asking for authorization of my computer to play a movie

Hello jchinlee,

Welcome to the Apple Support Communities!

I understand that you are trying to play a purchased movie from iTunes but are receiving repeated prompts to authorize your computer. In this situation, I would recommend working through the steps outlined in the attached article. 

iTunes repeatedly prompts to authorize computer to play iTunes Store purchases - Apple Support

Cheers,

Joe