@hiroko_tanahashi
Here's how to do multichannel audio routing with the Sound Player: https://support.troikatronix.com/support/solutions/articles/13000084953-tutorial-getting-started-with-multi-channel-audio-in-isadora
Currently, this functionality does not exist in the Movie Player actor (it is a planned addition for the future but right now we're busy with IzzyCast). That being said, it is possible on macOS to use Isadora's Move Player actor with multichannel video files that have been set up in a specific way: https://support.troikatronix.com/support/solutions/articles/13000069104-playing-movies-with-multichannel-audio-on-macos
Best wishes,
Woland