js video player not working in production environment - what could be the problem?

Question

JavaScript

I am developing a site on Rails 3.2.17, I set the task of adding a video player. In the development environment, everything is fine, the player works, I did not notice any bugs. In production, the whole player breaks, for example, the play button is not removed when playing a video, etc.
The only player that works fine both there and there is sublime, but it had to be abandoned due to one problem. Tried video.js, mediaelementjs, jw player.
I cleaned assets during deployment, I don't know what to do anymore. Has anyone experienced this strange phenomenon?
dartexpo.com/ru/zolotov-junwex-2014 here is the page with the player in production.

Answer 1

FF, Chrome - the player is working. True, the volume would not hurt to set 30 percent at the opening. It's not difficult, and the membranes are saved.

Answer 2

JW works, though the video starts with a wild pause.

Answer 3

If you are talking about what is small on the left, where the pictures change, then everything works for me. Scary but works