An Event is created for a single player, unless it is configured as a default in the pre or post-roll positions. They are not placed into a video.
When you select video(s) from your library and press 'Insert' in a GoVideo application, this creates a new player for those videos (with new UUID). This player will not have any mid-roll Events automatically generated in any circumstance.
Therefore, to be able to set a mid-roll Event for a GoVideo, you will have to add the Event after 'Inserting' the player into the email, but before it gets sent/seen by the recipient. This will involve going into the Vidyard platform and entering your personal account group during the composing stage of the email
To make the player easier to find, ordering your dashboard by 'date created' and 'descending' will show the newly created player at the top.