the above post is the method i used but here is exactly how i did it
1. Download RootExplorer
2. go into your /system folder and find build.prop
3. copy build.prop to your SD card (you might have mount r/w this is located on the top right in root helper)
4. long press the build.prop on your SD card and select text edit
5. scroll down until you find
media.starfright.enable----=true and change it to
media.starfright.enable----=false (there are 4 lines that need to be false)
6. Copy the edited build.prop to your /system it will say something like youd you like to replace this file say yes.
7. Reboot your Droid X
8.Enjoy your Video Playback!