Making it possible to tab to captions.

When a VideoAlpha is present on the page, if the user tries to tab through out the entire page, eventually he will land on the VideoAlpha controls. The tab index order has been set up so that all control receive focus eventually in the order from left to right. When a control receives focus, it is hilighted. The last tab focuses the captions dialog. When the captions dialog has focus, the Up and Down arrows can scroll it up and down.