Total Events are calculated as the total number of interactions with a tracked web page object. On the other hand, where a single user session (or visit) has one or more events, this is calculated as a single Visit w/Event, or Unique Event in the reports.
For example, if one user clicks the same button on a video 5 times, the total number of events associated with the video is 5, and the number of unique events is 1.
Why are Unique Events be greater than Total Events?
Here is a great short explanation on why this could happen.