This issue is about the media player in appmaker showing the video twice. After playing around a bit I found out that this does not happen if you simply use the default url when the player is created, it shows two videos when you change the url and save it. When it loads, it becomes like the screenshot below. It also happens when you change the url and then duplicate it.
I didn’t look at the issue for a few days and when I pulled the newest codes… Actually I don’t remember what I did but anyway, I couldn’t run it so I posted on the issue page what my current status is. The last time I was able to run it, I was using Chrome’s Developer Tools, added some breakpoints and from what I observed (not 100% sure though, this is just what I remember) is that it is creating the media player 2x. I’ll look into this again soon and try figure out what’s happening.