PIR + Arduino + Processing

Hi guys! I have a project to do and I need some help!
What I want is that three PIR´s will play different videos, like if has just one acting would play video 1, and if there´s another sensor acting together will play video 2 and finally if has the three acting it´ll play video 3.

What I was thinking is to save the PIR´s signals to an array and after that read it and save in a variable a value depending on how many sensor was acting and then send it to the processing to open the video, so I´m new using arduino and don´t know much about processing, if any one could give me some help about what part of come should come to arduino and what part in processing. And some help with the code!!