We present video content to end users and I've recently had a user report that they are unable to view the videos (loaded using JW Player 7 self-hosted) in any of the HTML5 supported browsers (IE11 11.9.0060, Chrome 46, Firefox 42).
We have tested in these browsers repeatedly before going live and we were never able to re-create the issues reported by this end user
Here is the code that is used to instantiate the video player:
Can you have them try another computer in the same office? What about in an incognito window? What about on their phone in the office's wifi? Yeah i suspect the content is possibly being blocked. As @Antiga said, have them look at the network tab to see what other calls are being made, and check to see the http code, they should all be 200.