User blog comment:Sarah Manley/ Product Update - Video/@comment-93604-20120320211436/@comment-1613840-20120320225629

The video player in the lightbox has a set height of 371px, and the width will adjust depending on the aspect ratio of the video. So for youtube, the aspect ratio is 16:9, so the width would be 660px. If a video has a different aspect ratio, this width will adjust.