Jim Buzbee writes "Interested in Google's VP8 codec? Well, so were the FFmpeg guys, so they went ahead and wrote their own native decoder in only 1,400 lines of unique code. They were able to keep the line-count low by relying on heavy reuse from the existing H.264 codebase."
Computers are unreliable, but humans are even more unreliable.
Any system which depends on human reliability is unreliable.