HI,
I’ll try to answer this as it’s my handiwork. It is a bit complicated and has been achieved using some handwritten code and some construction in Freeway.
On the page there is a layered object (let’s call this item1 for sake of clarity). It’s hidden using CSS, and it has a white semi-transparent background. This item contains another item (item2) which is the movie container (actually an iFrame).
When you click on a View Movie button, JavaScript is called which sets the position and width/height of item1. It also determines the position and size of item2 (so it’s centred in the window) and, using the Scriptaculous library (Protaculous - ActionsForge) fades it in. The JavaScript also sets the source of the iFrame to be the page containing the movie.
When the close button is clicked, the reverse happens - item1 is faded to transparency and hidden again using CSS.
You will find that pages opening tutorials also do the same thing.