A number of Youtube viewers are available for Joomla, but all the ones I checked have the same problem. They install the entire Youtube video player and start downloading the video before the page is fully loading, causing a long hang for end users. This small script instead displays a picture of the video and puts a play button over its top. The Youtube player and video itself are not loaded until the user clicks on the link. Here is a demo.
After trying to get my website working with other lightboxes, it seemed a good idea to make a new one, Most responsive lightboxes require very large libraries and are not easily customizable. So I wrote my own for this site. Here is a demo.