DirectShow is the default video decoder on Windows. If you'd prefer to use QuickTime, or want to compare performance between DirectShow and QuickTime, you can force QuickTime to be the default video decoder.
To do so, download the Force Quicktime Registry Script. Double click the script to run it.
If you then wish to revert back to DirectShow, download the Use Direct Show Registry Script Double click the script to run it.
Note: Some web browsers may add a .txt extension to a registry script once downloaded. If the script doesn't run when you double click it, ensure that it has a .reg extension and not a .txt extension.