If you've turned it off, what you see is not picture-in-picture.

Hello Picture-in-Picture https://support.mozilla.org/en-US/kb/about-picture-picture-firefox Is it, about icon, into the url bar. You can try 1 - Go to configuration editor https://support.mozilla.org/en-US/kb/about-config-editor-firefox 2 - Enter a search term '''media.videocontrols.picture-in-picture.urlbar-button.enabled''' You can double-click on the preference to set the value to '''false''' Or An other subject, about, other floating videos, but, is not always easy, to find the required information. https://support.mozilla.org/en-US/questions/1532254