iPod Can't play music/videos off iPod on Mac

I'm a bit stuck. I used to be able to play music and videos from my iPod in iTunes on my Mac, which was great because my media is stored on an external drive. So, when I'm out of the house with my MacBook, being able to use my iPod (which I sync automatically with my entire iTunes Library) would work fantastically. Do I need to enable manual syncing for this to happen? Because right now, all of the songs and videos are greyed out.

Okay I figured it out. The iPod has to be set for manual sync. It works now. Maybe Apple can make it so u can keep auto sync on and still use the iPod as a portable library?