YouTube has announced the start of testing a new feature that will allow users to leave comments based on the length of time they play. This will allow other viewers to see what other users are writing about different points in the videos.
Since this is just an experimental feature, it is only available to a very limited number of people. To enable this function, you need to go down to the comments section and select sorting by playback. When this option is enabled, pop-up comments will appear in the video player following from the playback bar.
It is worth noting that a similar feature has existed for quite some time in the SoundCloud music application. It allows you to find out what users write about at any moment in the track. YouTube decided to do the same.
Unfortunately, so far there are no screenshots of what it looks like, but there is official information from the summary in the YouTube Help section, so the function is really implemented.