Noticed on the latest release of Firefox after I press quit(I have multiple windows) the process will not fully close; I've confirmed this on both Windows and Ubuntu versions. It seems to happen when I have videos playing while closing as they will continue to play in the background. Only way to fully close the app is to stop the running background process; the videos cannot be stopped as they are CCTV streams. I'm not familiar with logging with FF if someone can advise on which ones would be of interest I can provide them.