how to convert ipod movie back to regular size

I downloaded a movie and then i converted it to the small size so i could put it on my ipod.. well i deleted it off my computer cause i already had it on a disc. anyways i went to copy the disc and it said disc cannot be read, so instead of having to downlaod it again is there a way i can take it off my ipod and convert it back to normal size without losing the good quality??

You can convert it back it up but the quality is gone forever.

You might as well just play the ipod file on your computer.