You can upload as many images as you like to each map location through the "Upload/Insert" buttons located in the location settings. Upload your locations via standard Wordpress media uploads, and each will automatically be added to the gallery, thumbnails created, and gallery functions added. To continue adding more images, simply click "Add Entry" and a new upload interface will appear.
To add a video to the pop-up window: Each location allows you to include an optional video in the pop-up window. To do so, simply enter the embed code from your favorite video site into the field called "Video Embed Code", which is found on the Map Location entry.
For example, if you want to include a video from Youtube, it would look like this (note that you must add the proper iframe close tag):
<iframe width="472" height="316" src="http://www.youtube.com/embed/u0fk6syQ7iY" frameborder="0" allowfullscreen> (close iFrame)
Here's how it looks in the admin: