I started a new firefox profile and I had to reconfigure several sites to allow audio and video to autoplay. That kind of thing should be enabled by default for sites like youtube twitch pandora etc. Otherwise pages load but content won't start until you click play which is annoying. I have had to click on the padlock icon in the address bar, then click connection secure, more information, permissions, autoplay, allow audio and video for every site that has some kind of audio and video on it.