We've recently heard from some customers who have added videos on their home page in either the ShowTime or Galleria themes letting us know that they aren't autoplaying or loading in the lightbox windows as expected. We discovered that the issue is related to the video URL that is pasted in for these videos.
In the case of a YouTube video, you might right-click on the video in your browser and choose Copy video URL to get the link to the video. The URL that is copied looks something like this:
This is a shortened URL that actually takes you to:
Unfortunately, the shortened URL does not work properly with the themes. The longer URL is what should be pasted in your theme settings. To get this link, simply open the full video page in YouTube and grab the URL from your URL bar.
We apologize for the inconvenience caused here and are looking into the possibility of updating the themes to support either URL type.