I believe you will need a script to do that.
I found this posts that explains how to run something after a Youtube video has ended.
I tested it inside a page content and it worked fine
http://stackoverflow.com/questions/7853904/how-to-detect-when-a-youtube-video-finishes-playing
For info on implementing scripts in Xtreme, you can read the tutorial below in the new Guide site.
http://guide.weavertheme.com/scripts-using-them-for-advanced-styling-or-design-changes/