If you want to keep track of what part of the video people watch (or skip), you can add progress flags.
These behind-the-scenes markers divide your video into small segments. The viewer doesn't see or notice this setting. You set the progress markers to extract more info from the video statistics. You can see very precisely which points (flags) in the video have been viewed. Of course, also this feature is available per view session.
How to set up the progress flags
Go to the Video settings
Go to the tab Collect viewer data
Click on Add markers to track video progress
How to read the progress flags statistics
Go to the video statistics
Scroll down to Export statistics
Export the video progress sheet
Green and red cells indicate which flags were passed during a viewing session.
Of course, also this feature is available per view session.