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.