It seems I can work around the problem by manually removing the "&s_id=xxx" portion of the page URL.
For example, if you navigate normally to the practice tune page, the URL is
"https://www.guitartricks.com/lesson.php?input=28846&s_id=2443"
I manually delete the "&s_id=2443" and you get:[br]"https://www.guitartricks.com/lesson.php?input=28846"
Reload the page, and now the video works all the way through. Can tech support please use this information to troubleshoot this bug?