A Montage is a highlight of the moments in the bubble. It can be seen by others who you have invited to the bubble, but it will NOT be available for viewing in the public widget unless you publish it explicitly. Burst creates Automatic Montages for you. Montage options can be found under the Edit Bubble options.
You can use the WOW button on the Burst App camera and player to mark the highlights that you want to include in your Montage!