Use of the requested audio unit(s) require lowering the security settings
I have come across one (!) reply on the Apple boards.

I want anyone who reads this to take it with a grain of caution. This 'answer' does not seem to ring as '110%' accurate.


  You are using a Codec component that is not compatible with macOS Sierra. That Codec component was a part of a library that conflicts with macOS Sierra and in order for Quicktime to load would require to change the "Quick Look UI Helper" security settings. If you really need that Codec component you can proceed by clicking "Quick Look UI Helper" Lower Security Settings.


(Here's the link; https://discussions.apple.com/thread/7948198?start=0&amp;tstart=0)