Thanks for sharing what worked for you, jared1.
That forum is the official forum for Shadowbox. We go there often when we need help :)
Whenever someone has a problem with Ninja Shadowbox (our implementation of the Shadowbox script), I suggest using a different extension on the JED called Shadowbox Media Viewer (the one you found).
The reason for this is that the version of Shadowbox in NinjaShadowbox is old. The Shadowbox Media Viewer plugin has the latest version of Shadowbox in it, and they are the only authorised distributors of that version of Shadowbox. We are not permitted to put the latest version of Shadowbox into Ninja Shadowbox.
When Shadowbox was first released, it had a GPL license. In version 3.0, this was changed to a proprietary license, requiring anybody who uses it on a commercial website to pay a fee.
We had two options... either stay with the GPL one, or stop distributing Ninja Shadowbox altogether.
We stayed with the GPL one. The downside being that since it has not been updated in a year or two, bugs occasionally pop up when using the plugin with new browsers... especially with video media, as you discovered.
I'm sorry we couldn't provide you with a good experience.
Have a good weekend, jared1.