Rented movie, importing it as .m4v file and it comes without sound.

I've rented a movie in my ipad but then I wanted to watch it in my computer. I tried through iTunes and couldn't do it. Next I used DiskAid, an app in my computer to access the files in my ipad. I found the movie in the "Purchased" folder with a codified name and then copied it to my computer, once it was there, appeared as it was playing but there was no video or sound.

Thanks for your assistance.