Please note, I know how to mute a tab and change volume in an individual video player, that is not my question. Prior to version 56, it seemed like all custom HTML5 video players (except Flash) respected the Windows per-app volume level set for Firefox. If I set my Firefox and Flash volumes really low in Windows, I could rest assured the volume would always be low. After the 56 upgrade, it seems like every custom HTML5 player has its own custom volume level. Not only does the player not respect the per-app level volume of Window, it defaults to 100% volume, and doesn't have an app-level volume to adjust. It seems to me that, if I set Firefox's app-level volume to a particular level, all sounds made by the app should respect that audio level. Is there any way to make that happen?