Got an interesting one. If you click on the video title within the context of a members profile (within their activity stream or within their media folder) the lightbox pops up. But if you do it on the individual item page or the main activity stream, it does not.
On your demo site, I had to switch to the Twenty Fourteen theme to reproduce it, since you dont provide title links to trigger the lightbox on your fancy new theme In any case, on your site, it does pop up in the main activity stream but not on the individual item page. Check it out
http://demo.rtcamp.com/rtmedia/members/admin/activity/4312/ (make sure you switch to twenty fourteen).
If you look at the console, it just keeps firing the GET request over and over without any error messages.