Greasy Fork is available in English.
Buffers the video without autoplaying and puts it in HD if the option is on. For Firefox, Opera, & Chrome
< YouTube Auto Buffer & Auto HDについてのフィードバック
I'm still using Flash on Firefox 37. Maybe you can change it on this page: youtube.com/html5.
Hi. Was a bug in Firefox 36/37.00 from what I recall. They've fixed it now. Thanks for the nfo.
YouTube Select Player
Hi. With Firefox 37, for some reason you can only use HTML5 video player. Not sure if you can add an option to select which video player to use?
Tried installing the following but doesn't work with your script. Video always plays (ignoring "stop loading immediately").
https://addons.mozilla.org/en-us/firefox/addon/youtube-flash-player/