In the movie "The History of the World - Part 1" by Mel Brooks, what
was contained on the tablet broken by Moses? It was, supposedly,
commandments 11 - 15. What were the commandments. I think they were in
Hebrew.

Nothing. It was a joke :-)

Visit the following web page:

Cat Hate UK - Gleanings
http://www.cathate.co.uk/gleanings.htm

According to this page, a contest has been run on The Guardian (
http://www.guardian.co.uk ):

"In Mel Brooks' film The History of the World: Part I, Moses descends
from Mount Sinai and drops a third tablet of stone, so destroying
commandments 11-15. What might these missing commandments have been?"
One of the responses was -
11. Thou shalt not drive at more than 30mph in a built-up area.
12. Thou shalt not suffer thy cat to use thy neighbour's garden as a
toilet.
13. Thou shalt not curse thy supermarket trolley. It knoweth not what
it doeth, and neither do youeth.
14. If a cyclist should smite thee upon the pavement, thou shalt not
shove him into the oncoming traffic.
15. Curse not thy neighbour's barbecue, for a burnt sacrifice is
pleasing unto the Lord.
Robert Hill, Reigate, Surrey
October 2000

I don't think they were meant to be real words or not.  But here is a
screenshot from the movie:

http://www.ladyofthecake.com/mel/world/hwimages.htm