Greetings, I've been having this issue for quite some time now and instead of just switching to another browser, I've come to the point where I've decided that it's time to fix this issue. It took me quite some time to figure out but now that I have, it's time to take it on. I frequently watch videos from various sites, both common and not so much but this happens across the spectrum. I usually have auto play off and volume muted because I'm in a super quiet building and one never knows how a video will start out unless we're familiar with the site, content, etc and have had some instances where a video would auto play and the volume would be cranked and I'm usually either Bluetoothed or wired to my home audio system so needless to say, I'm sure I've startled, surprised, or otherwise affected other tenants here, not to mention some embarrassing ones. Oh well. So now to my issue. For the past few months, possibly more, it could even be over a year now that I think about it, when I play a video, it's fine with the volume muted but when either I turn the volume on, or shut the mute off so that the videos will start with sound, they won't play. Some not at all and they won't even start, some will start for a split second and then stop, some will play for varying amounts of time, however usually not very long, and once in awhile one will play for a few minutes. I can't remember the last time a video played all the way through with the sound un-muted. It's been a while. This isn't an issue in any other browsers that I know of nor playing local content on installed media players. It's only firefox and it's any online streaming video from any site.