I opened https://1drv.ms/v/s!AsJczvumFGUR8j9mnGkuCLOu_X6C and had the same no audio problem.

I downloaded the file, and it played just fine.

See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

On the OneDrive video, if I right-click and choose Show Controls, there is a mute symbol that seems to indicate Firefox is unable to handle the audio (first screenshot).

When I view the video in Windows Media Player on Windows 7, it is silent. This may explain the problem, because Firefox uses Media Foundation and if Media Foundation does not support the audio in this file, neither can Firefox.

When I view the video in VLC, it plays fine. The audio codec shows A52 audio (AC3) (second screenshot). I don't know if that's a common format Windows Media Player should be able to play, or something more obscure.

To answer some of the responses:

1. 1. I wasn't referring to downloading the file, only streaming.
2. 2. I can't get any menu to come up by right-clicking that says "Show Controls."
3. 3. We're not talking about Windows Media Player here, only browsers that can playing streaming audio/video. With Windows 10 and the Edge browser, the video plays fine, both audio and video. With the latest Firefox for Windows 10, there is no audio sounding, but it is in the mp4 file. What's wrong with Firefox?
4. 4. The other Issue is that the film (the 2nd link) never loads properly for streaming in Firefox, only an endless spinning arrow. It plays fine with Edge.
5. 5. Both these issues have been replicated on other computers by different users. Perhaps Firefox is not robust enough to handle streaming files?

I think you need to rethink your # 3 as it seems your not understanding what was said about Firefox uses Media Foundation and is based on what ..... It was suggested you update your video card to watch the video, it is noted that there is errors we can see. Please do so. As bad video drivers can make sound issues. https://www.geforce.com/drivers

You can try this to see if something is blocking the sound that is running https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode and https://support.mozilla.org/en-US/kb/html5-audio-and-video-firefox and https://support.mozilla.org/en-US/kb/fix-video-audio-problems-firefox-windows and https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues

And hoping that this is all fixed in Firefox 57 Quantum release date Nov 14th https://www.mozilla.org/en-US/firefox/quantum/ Note : Legacy Extensions will be disabled and or removed.

Please let us know if this solved your issue or if need further assistance.

prman said

4. The other Issue is that the film (the 2nd link) never loads properly for streaming in Firefox, only an endless spinning arrow. It plays fine with Edge.

This plays normally for me in Firefox 56 on Windows. Some DoubleClick ad content may be called/served, and our different add-ons may have an effect on what happens at that point.