Prevent embedded video appearing above image overlay http://www.fareham.ac.uk/news/2011/10/17/skins-star-inspires-students

The above page includes an image gallery, powered by the Brilliant Gallery module.

The problem: when a thumbnail from the Gallery is clicked, the embedded YouTube video beneath the Gallery section appears above the image overlay (powered by the Lightbox2 module).

How can I prevent this from happening?
It is a matter of wmode