How do I get QuickTime to store temporary recordings on another drive? When you do a movie recording or screen recording, QuickTime stores the in-progress recordings in ~/Library/Containers/com.apple.QuickTimePlayerX/Data/Library/Autosave Information.

On my machine, I have a fast SSD mounted on /Volumes/SSD but a slow platter drive on /. I'd like to send the autosave files to the SSD. With professional programs like Premiere, you can just set the scratch location, but with QuickTime it seems impossible. However, I really like QuickTime's screen recording feature and would like to use it with my fast SSD.

I tried to ln -s the Autosave directory to point at my SSD, but QuickTime errors out with an "unknown" error after that.
Turns out this is actually possible by employing a double link trick. In the terminal:

$ cd ~/Library/Containers/com.apple.QuickTimePlayerX
$ mv Data Data_bak
$ ln -s /Volumes/SSD/QuicktimeScratch DataSSD
$ ln -s DataSSD Data


and voila! This sets up Data as a link pointing to the local DataSSD file, which in turn is a link pointing to the actual SSD scratch location.

QuickTime works fine now, and puts its temp files on my SSD just as I wanted. No more screengrab stutter!