Firefox keeps being updated, and some updates are just plain stupid.
I’m talking about the different behaviour of Click-to-play feature, which now remembers settings per site, and automatically launches the plugins on this site. This leads to YouTube video starting to play immediately on page open. I don’t like that, I like to open several pages with different videos, and then launch the required one by clicking on the player. As it was before! There is a way to fix it though. First, you need to dump all site preferences. In Firefox, press Ctrl-Shift-Del, tick Site preferences and delete them. A good sign you did everything right is a nagging popup toolbar asking you to allow Flash when you open YouTube or any other flash-enabled website. Now open advanced configuration by entering about:config in the address bar and clicking enter. Here you have to make sure that click to play is on, by manually setting this parameter to True. Also, reduce the time Firefox keeps site preferences from 60 to 0. Go check Flash plugin settings in addons window – it should be always ask. Now when you open a YouTube video, a grey rectangle will appear, clicking which you get to another toolbar, where you click Allow for the video to be played. Not exactly convenient, huh? Well that’s one of those recent Firefox improvements that drives me nuts. They want the user to be aware of Flash being a vulnerable piece of shit, so be aware again, and again, and again, and again. To get rid of it, we will have to use an addon. My plugin of choice is Click to play per element. It restores the single click functionality as it was before: the page opens with the plugin stopped, you click on the player placeholder once, and it opens and starts to play the video. Another good similar plugin is Flash Control and there may be some others.