Downloaded a movie, and now its gone!!!!

When i first purchased my Ipod Touch 32G last year, one of the first things i did was purchase a movie. I bought 2012. I watched it many times on my ipod, and also to my laptop. After about a year went by i had not used my ipod for a few months and when i went to go use it again the movie was still there. then i hooked it up to my laptop to install a newer version of I tunes. when it was completed, 2012 was no longer on my Ipod but was on my laptop still. Why did it remove the movie from my Ipod and is there a way i can get it back???? I paid 15 dollars for that and i feel like i got ripped off. and is this going to happen again if i purchase another movie, havent purchased another since???