That's correct. You can revert back to stock after using Autonooter but once you root CM7 reverting back becomes more involved. I know because I found out the hard way myself. (See an older post of mine on recovery.) There is a better way if you plan ahead but I hadn't. The important thing to remember though is that it's very difficult to brick the Nook so there's almost always a way out. Even now I haven't bothered with making a backup of the stock OS. There is nothing on it that interests me anymore. If and when I need it for some reason, I'll deal with it then.
Huskermania's videos are great! Even though I prefer to get my hands dirty, I watch his videos as a precaution in case that I missed something.
Good luck with your rooting!