Flash PLayer 9 Installation

[I am a linux noob] Looking at this guide

http://www.howtoforge.com/native_linux_flash_player9_in_ubuntu

Can someone please tell me why I have this:

Please enter the installation path of the Mozilla, SeaMonkey,
or Firefox browser (i.e., /usr/lib/mozilla): /usr/lib/mozilla
dir= /usr/lib/mozilla

WARNING: Please enter a valid installation path.

Please enter the installation path of the Mozilla, SeaMonkey,
or Firefox browser (i.e., /usr/lib/mozilla): /usr/lib/mozilla
dir= /usr/lib/mozilla

WARNING: Please enter a valid installation path.

Please enter the installation path of the Mozilla, SeaMonkey,
or Firefox browser (i.e., /usr/lib/mozilla):



But when I enter

/usr/lib/mozilla-firefox

It works.

I do have a /usr/lib/mozill directory with plugins folder in it.

Please help, I want to understant what is going on.