If you have installed VLCtube Greasemonkey script, disabled the "auto enabled subtitles" checkbox but still occasionally want to see subtitles (for example music videos with lyrics) my little cript will highlight VLCtube's subtitles button. It's a sort of "notification" that the video has subtitles (because most videos don't have subtitles).

Example of a video that has subtitles
https://www.youtube.com/watch?v=y6Sxv-sUYtM

VLCtube script:
https://github.com/jackun/VLCTube/blob/master/25318.user.js
(click the "RAW" button)


VLCtube is a great script. Among many great things it is The ONLY script which really solves YT's low-volume videos problem.
I've explained it in my review:
http://userscripts-mirror.org/reviews/45636/

See also my http://freestyler.ws/style/101169/vlctube-longer-volume-bar-on-the-buttons-row