The tabs seem to be working ok, the cart is functioning, video plays in the tab.
The only think i see strange with firefox is that the gallery display breaks out to the left when you click on an image. It may not do this in other browzers. You might try changing the settings of SIG PRO and see if this helps>

when i edit item.php, i usually leave all the events in the code and remove only the display of the k2 elements i do not want to show, or rearange them

Thx for the feedback William, I just wasn't sure what all the before / after display really meant, I didn't move much code I think, I will try a different SIG Pro popup code too, thx again.