Some YouTube videos have helpful "timestamps with descriptions" to help navigate the segments of the video, which are called "chapters".
Not all authors go through that effort, though. When a video does not contain "chapters"/"timestamps with descriptions", you can quickly copy the video title, then search for that on Google's search engine, and it will likely return an "automatically chaptered" video.
Example:
This video of Richard Feynman: https://www.youtube.com/watch?v=36GT2zI8lVA does not contain "chapters".
However, this search query, simply copy pasting the title, returns one with "chapters", labeled as "key moments":
https://www.google.com/search?q=Richard+Feynman.+Why.&oq=Richard+Feynman.+Why.
Not all authors go through that effort, though. When a video does not contain "chapters"/"timestamps with descriptions", you can quickly copy the video title, then search for that on Google's search engine, and it will likely return an "automatically chaptered" video.
Example:
This video of Richard Feynman: https://www.youtube.com/watch?v=36GT2zI8lVA does not contain "chapters".
However, this search query, simply copy pasting the title, returns one with "chapters", labeled as "key moments":
https://www.google.com/search?q=Richard+Feynman.+Why.&oq=Richard+Feynman.+Why.