Recently, YouTube added a feature to add live, interactive chapters to videos. Implementing it is easy. Just add a table of contents to the description.
Many videos already have a TOC. The only extra thing required is to add the first entry as 00:00. See details below.
Now, if you already have many videos, what to do? Find videos which already have a TOC. Go to the first line of TOC and add the Intro – 00:00 line. That’s it. That is exactly what the YouTube Chapter Creation Tool does automatically for you.