There are a number of settings in QuickTime X which are not exposed in the Preference panel or the QuickTime Player app. These are two QuickTime-related CLI tools included in Snow Leopard that you may be interested in for exploring these settings, and adjusting their values:
-- lets you set and reset many of the items formerly found in the QuickTime Preference panel.
-- talks to IP-based encoder boxes used for HTTP Live Streaming.
Read the man pages for these tools for a description of the settings they can affect and how to use them.
There is also an excellent set of AppleScripts
for managing hidden preferences in QuickTime X. The ReadMe file on the disk image documents what the scripts do, suggests a few other commands, and states how to restore things to default condition. Thanks to Sal Soghoian of Apple for pointing out the existance of the scripts.
I tested some , but not all, of the AppleScripts, and they work as described.]