I appreciate the effort that it takes to write plugins so no hating here, just comment on why this wasn't a solution for me. Firstly, as others have said, it takes a while to kick in. It plays a few seconds of the video before it is stopped. This is annoying (mostly for my neighbors). Secondly, the stopping pre-load feature effectively means that one has to click twice to start the video, once to stop pre-load and once to start the video. I used the suggestion that itge13 made in one of the comments (the simple change to the config file) and it works well, so I uninstalled this plugin. It needs a bit more work but on the other hand, the about:config method is quick, easy and works (in Firefox at least) so I see no point in further development.