videos downloaded with download helper have no audio
When I download a video using download helper, the video plays fine but there is no audio. What do I need to do to fix that?
I assume you are talking about the Video DownloadHelper add-on?
If you are, it's usually best to reach out directly to the add-on developers for help. Only a few add-ons are actually developed and maintained by Mozilla. The others are owned by independent third-party developers.
The developers offer this website for support with their add-on.
Hope this helps.