Global Settings for Media Items

One of the valuable aspects of the scripting support in Keynote, is AppleScript’s unique ability to manipulate, with a single script statement, the properties of slide objects that are placed throughout the document. For example, you can set the playback settings for every audio clip in a presentation with this script:

Or set the volume of all audio clips to the same setting with this script:

Make a slight change to the audio clip volume-setting script  (⬆ see above )  and it targets all of the movies in a presentation:  (⬇ see below ) 

Other properties for movies that can be set globally include: locked, position, opacity, width, reflection showing, reflection value, and rotation.

Other properties for audio clips that can be set globally include: locked, and position.

You can even create a script that sets multiple properties for every movie, audio clip, image, shape, line, table, chart, etc., as with this script that sets multiple movie properties globally: