The Australian Ong Bak DVD has tons of extras. There are 5 easter eggs but so far I have found 4. I can't find the last one.
I have found the following Easter eggs:

Easter Egg 1: Highlight 'The 8 Muay Thai Movements' and press Right to highlight a fist. Then press the 'Enter' key and you’ll see "Director's interview and Alternate Ending" (2.47).
Easter Egg 2: Go to "Artwork Galleries" menu, highlight 'Storyboards Gallery' and press Right to highlight a fist. Then press the 'Enter' key and you’ll see "Director's interview and 4 Storyboard Comparisions" (9.57).
Easter Egg 3: Highlight "Artwork Galleries" and press Right to highlight a fist. Then press the 'Enter' key and you’ll see "Director's interview and 3 3D Animatic comparisons" (3.13).
Easter Egg 4: Go to 'Trailers and Bonus Materials', highlight "Back to Extras Main Menu" and press Left to highlight a fist. Then press the 'Enter' key and you’ll see "Director's interview and 2 Deleted Scenes" (7.16).
Easter Egg 5: Unknown - Title 20 (5.01). <- can't find!

Can you help?

Cool Thanks man I'll look for the 5th one

I found the 5th easter egg! But it only can be accessed by Window Media Player or Nero Showtime.
It is Title 20. It is a demo reel of tony jaa's skills which was presented to the director.

I clicked on the "root menu" button and it led me to the "Tony Jaa Demonstrations" menu. So there must be the button on this page that is hidden or maybe the button doesn't work. Someone should contact Eastern Eye!