why is 0! equal to 1! ?

That is what the video said Chris.     :)

I guess it is nice ot have it in print in front of your nose sometimes though.  So thanks :)

Here you go.

https://www.youtube.com/watch?v=Mfk_L4Nx2ZI

Thanks for asking this question. I really enjoyed the video clip.

It starts at the very beginning - explaining what factorial means.

Then if progresses to gamma functions.

so there is something for almost every one.

ALSO

The is a clip from the    Numberphile website   I'll bet their other clips are just as interesting.  

Here's a rather simplified "proof"

3!  = 4! / 4

2! =  3!/ 3

1!  = 2! / 2

So

0!  = 1! / 1  = 1