To add video or audio to your event description, the video or audio file must be hosted on a video/audio hosting site like YouTube or SoundCloud.
Copy the embed code from the media hosting company and inside VBO go to OPEN EVENTS and select the "edit event info" from the select action menu next to the event you want to modify.
Scroll down to the Event-Related Messages area. Paste the code into the Embed Video or Embed Audio area. Add an optional title and then paste in the video embed code and press SAVE.
NOTE: If you do not want to use YouTube, make sure your host page utilizes https:// in the URL, or your page will display a security warning.