Separate video decoding in another process

Submitted by Bastien Nocera @hadess

Link to original bug (#664256)

Description

To cut down on the possible crashers in video applications, as well as to protect the system from security problems due to crafted videos that would be available on the Internet.

This process could then be locked down based on technology available in particular systems, and with the process also setting itself up to be as frugal as possible.

For reference, QuickTime's process separation:
http://arstechnica.com/apple/reviews/2011/07/mac-os-x-10-7.ars/9#privilege-separation
Google Chrome's sandboxing:
http://en.wikipedia.org/wiki/Google_Chrome#Security