Hi Soundless_Cyborg, Can you please specify an example url where this is happening, sometimes the video player does not support the codec.

Maybe you need to set it as default for this file type:

Open Control Panel > Programs > Default Programs > Set your default programs > Select Windows Media Player from the lists under Programs > Set this program as default > OK

Tried to set it as the default, and no noteable changes, I'm afraid.

I am using both tumblr's video player (which uses .mp4), along with the vine video player. The two videos I'm specifically using are:

https://vine.co/v/OmZgBjziQ2M http://vronboo.tumblr.com/post/99467016420/when-a-smash-fight-accidentally-becomes-a-jojo

Man, this works for me. But then again I am using a virtual machine window s professional (64bit). The one different really is that the drivers are blocked on mine. I should have suggested this first: try to disable hardware acceleration. If you start Firefox in Safe Mode this should be something that is automatically disabled/ Upgrade your graphics drivers to use hardware acceleration and WebGL and Diagnose Firefox issues using Troubleshoot Mode

Tried Firefox in Safe Mode, no audio. Tried to disable hardware acceleration outside of safe mode to see if it'd work, but unfortunately, the problem of audio-less .mp4 videos persist!

Try to update the flash Player or Mozilla itself. Hope it will get the audio back.

Firefox updates automatically, BUT I opted to give it a try anyhow, since it couldn't hurt. No changes in the missing audio, I'm afraid.

My flash player last updated on the seventeenth, and though I forgot to mention it in the first post, I've been having this problem for many months.

So unfortunately, neither had changed the case. Curses!

No replies, but the problem continues to persist. I hope no one minds me bumping this thread, but does anyone else have any idea of what I oughta do?