add songs to contents of music in iMovie

Songs that are DRM (Digital Rights Management) protected, such as those that originated from Apple Music in the chain of purchase or were purchased from iTunes before Year 2009 cannot be used in iMovie.

-- Rich

To cover the bases, here's an online help link that explains the process from displaying songs in iMovie:

https://help.apple.com/imovie/mac/10.1/#/mov91a895a64

-- Rich