Like a Master widget, a Master view displays a set of widgets defined in a master template. A Master view, however, unlike a Master widget, cannot be placed directly in a template. It must always be used in combination with a Content Body widget widget. The Content Body widget then delegates rendering of content to the Master view.
To use a Master view once you have configured it, you must drop it on the Related view field of a Content Body widget widget. The idea is that you drop several differently configured Teaser views and/or Master views onto the Related view field of a Content Body widget widget and then configure them to select different types of content item from content items that the parent delegates to them. This enables the Content Body widget widget to present different types of inline content item in different ways.
A Master View, therefore has two different sets of properties that are configured in different ways:
Properties that govern the Master View's appearance and behavior when rendered. These are similar to the Master widget's properties, and are edited in the normal way
Properties that govern the selection of delegated content items. These properties can only be edited after the Master View has been dropped on a parent widget's Related view field.
The Master view was introduced specifically to enable use of the Widget Framework's video playlist functionality for inline videos. For details, see /widget-user-guide/4.6/media_player_playlist_for_in_line_content.html.
Please note that /widget-user-guide/4.6/lazy_loading.html will not work with the Master view.