Youtube now extracts chapter markers from the description of any video, the ideal markup is shown below (although it is somewhat flexible and tries to accept some variability).
00:00 Intro
00:38 Design
04:15 Touch ID
06:21 Display
07:57 Performance
09:27 Wireless
10:35 Battery
13:09 Cameras
16:57 Price
Rules:
- Each chapter gets a new line
- There must be a 00:00 callout (it triggers processing)
- At least 2 chapter markers (lines) must be present
- No more than 25 chapter markers per video
Given the above constraints, it will segment the video progress bar accordingly and will also highlight by name the current chapter next to the time at the foot of the video.