Randomizer Script that excludes files it chosen from being picked again?

I have a site: https://salty.link and I've got a script that picks a random video and displays it.

Question I wanna know is sometimes videos repeat them-self to much. So what are some ways to go about not repeating videos and only repeat them once all files from Directory have been randomly shown?

Here is code:

http:// pastie. org/10632518 (sorry can't post more then two links.