Steps to repro:
1. Go to https://output.jsbin.com/fiqudin in Firefox
2. Click publish
3. Allow access to your camera
4. Open https://output.jsbin.com/fiqudin in Safari
Result: You get a blank video element
Expected Result: it starts playing back the video
If you click publish (which calls getUserMedia) in Safari and allow access to your camera then the video will immediately start playing back. Also if you already clicked publish previously then it will playback fine. It's only if you are trying to play back a remote video but you have not allowed access to devices.
This only happens between Firefox and Safari. It does not happen between Chrome and Safari, or between Chrome and Firefox.
I tried the example and updated the Safari "settings for this website" to disable the autoplay limitation. Then the example often works. Can you test this on your side?
I was able to reproduce one time where the decoder was spitting errors -308 and -8969.
It is still happening for me every time. Both using Safari 11 Beta and Safari Tech Preview with Firefox 55. I tried setting “Allow all autoplay” in the “Settings for this Website”. I tried setting Always allow Camera and Mic input. I also tried turning off “Video Needs User Action” and “Audio Needs User Action” in the debug menu in STP. I still have the issue every time.