If a user visits a web page with an embedded video, leaves without clicking on anything, and the session times out, how will Google Analytics report the session?

As a bounce

Explanation:

The options are:

As an interaction

As a click

As an event

As a bounce

And the correct option is as a bounce. You will find that Google analytics calculates the bounce specifically in terms of a session which gets triggered only as a single plea to the server, and which is the analytics server like the use clicks and opens a certain page on any website, and then exits without making any further request to that server in that session. And hence, this will be counted as a bounce.