What's an Event?
Usually an Event is a game.
But it could be almost anything. The only requirement is that an event must occur at a specific time, at a single location, and be related to at least one group/team.
A tournament, for example, consists of several events. A practice, photo session, or party could be considered an event.
An Event typically has multiple source videos files associated with it. These can be one per game period, or a single file covering an entire game, or several videos from many different camera angles.