Infanct, that is an incorrect statement! It works completely fine with any version of minecraft thanks to a brilliant piece of code written by Notch! It's most commonly referred to as scaevelous' mcregion! The only reason the download didn't work would've been the fault of either you, your computer's hardware, software or the tampering of minecraft's native files (the .minecraft folder)! With a mod, fix or incorrect code (the fault of which you)/paulscode or other native .class file changes!