The answer to How to record both screen and sound with Quicktime on El Capitan? explains what to do in order to record the screen using QuickTime player with sound (both from the micro and the computer).
I followed the steps there, and although I successfully managed to install Soundflower and to add a Multi-Output device, the screen recording produced by QuickTime player has no sound.
Is there a way to check whether the Soundflower works properly?
I'm connected to an Apple display as well, so does this pose an issue?