iMovie: safe to delete Render Files? I'm hoping to slim down the size of my 50gb iMovie library. I noticed that a huge chunk of space (like 20gb) is taken up by the contents of a "Render Files" folder in one of my Event folders. 


  You can see the "Render Files" folder by right-clicking/control-clicking your iMovie Library and choosing "Show Package Contents". Then open one of your Event folders. The "Render Files" folder is in there.


What's the deal with those files? Can I safely trash them? Will iMovie rebuild them?
Yes, and iMovie can even delete (all) of them for you.

Go to iMovie > Preferences and click "Delete" next to Render Files (last item on the bottom for me).



It will warn you about deleting data, and that it may have to be regenerated in the future.



Inspecting my iMovie library with Finder after this operation revealed that it cleared the Render Files directory and freed up ~60GB from my disk.