Each comment (in the Comment Space) and each note (in the Personal Notes Space) gets a timetag that reflects on what specific moment in the video it was added. Therefore every question, comment or a note is always in the context of the video.
Clicking on the timetag will take you to the exact moment in the video that it was written about.
At the bottom of the video, you can see the Annoto timeline that provides a visual representation of what was written in that space (Comments\ Personal Notes space).
The height of the bars represents the number of comments (or notes) & the colors represent their sentiments (if no sentiment was used, bar will be grey).
Clicking on a bar in the timeline:
Takes you to that exact moment in the video
Scrolls the discussion to its place
A high brown bar, for example, represents a place that includes many questions. It might be worthwhile to see what it's all about ;)