Video #87
In this video I use the Feature Action tool to configure a button to display a photo for any feature. The feature layers has a path (in the field "myphoto") to a photo on my local drive. That could easily be changed to point to any location e.g. URL
The video is an overview of mainly the OPEN action but does show you how to access other action types.
It follows on from Video #86 which shows you how to display a photo when hovering on a feature (using MapTips) but this video is where you want the user to be able to click a button to show any media.