Here's a simple way to extract You Tube video subtitles (only for those that are autogenerated or uploaded to You Tube and only if author settings allow I think)
without too many scripts and commands (but need your cut and paste skills)
Eg video is at https://www.youtube.com/watch?v=zcqZHYo7ONs
Use the video's coded name : zcqZHYo7ONs
and add to the end of this :
http://video.google.com/timedtext?lang=en&v=
And form the combined text below
http://video.google.com/timedtext?lang=en&v=zcqZHYo7ONs
Paste this into Chrome browser and you will see text eg.
<transcript>
.
.
.<text start="261.19" dur="3.28">
of a comet, what happens to the orbit of the moon?”
</text>
<text start="264.47" dur="3.67">
It almost sounds like a MinutePhysics video… but you’re going to have to go to Brilliant.org
</text>
<text start="268.14" dur="6.73">
to solve it (or one of their many others) – and when you do, use the URL brilliant.org/minutephysics
</text>
<text start="274.87" dur="2.01">to let Brilliant know you came from here.</text>
</transcript>
Other command line or browswer methods exist (by programmers) eg .
youtube-dl at https://github.com/rg3/youtube-dl
Youtube Auto Subtitle Download at https://github.com/1c7/Youtube-Auto-Subtitle-Download