code 4 – MEDIA_ERR_SRC_NOT_SUPPORTED – audio/video not supported
We do see this when unsupported compression types are used on the video, which is why we tried to put a friendly face on the error message. Digging a bit further as to why it would show up on a normal MP4 video, it looks like there are some server configurations and settings that you could adjust on your server that may solve the problem, but the easiest fix should be to make sure you are using HTTPS to server the content rather than HTTP.
Just to make sure I understand your situation, are you hosting the published content on your site, or linking to the CenarioVR site? When you re-upload the link to fix it, is it just the link, or are you re-uploading the content?
Here are a few links to some related topics on the Web: