It was used in Crash Course A&P. It is at 1 minute and 47 second. Here is the context.
It is kind of like this: you don't want to clean out your fridge just by taking out the rotten fruit and fuzzy leftovers.
I have checked all the meaning of the word fuzzy, but cannot get in which sense the speaker used it. Does he mean that he does not know what those leftovers were?