I first saw this tip on MacOS X Hints.com and kept it in the back of my mind. Their tip was for adding music to an iPod that is set to auto sync to another computer. For example, I auto sync my iPod video to my iMac at home (which serves as a media center for the house). It has ALL of my music on it and of course all the videos and such purchased from iTunes.

When I travel I carry my MacBook Pro which has a limited set of music and videos on it as to not eat up drive space. Every now and then I come across a song or buy something from iTunes that I would like to have on my iPod for the remainder of the trip. However, if you plug an auto sync'd iPod into another computer your options are to wipe and sync it to that computer or leave it alone.

This tip lets you copy the mp3 file from the Finder right into the source window of the iPod even though it's not sync'd to the computer you have it connected to! Cool!

On my most recent trip, my daughter brought along her iPod video and a DVD movie that she planned to watch. However, there was never really time to watch the movie and the only way to play it was on my MacBook Pro which I planned on using on the flight back home. So I wondered if the above tip would work for video? I gave it a shot and it did!!!

Steps:
I put the DVD in my computer and ripped it to an mp4 file using Handbrake 0.7.1 (took about 30-40 minutes)
I then connected her iPod video which is auto sync'd to her iMac at home, iTunes asked if I wanted to wipe it and sync it to my computer and I hit no/cancel. However, the iPod showed up in my source list with all the content grayed out.
I then drug the mp4 file of her movie into the grayed out list of content and noticed that I got the plus sign meaning that it was going to copy it and it did.
I then unmounted her iPod and went to the video list and it was there and played just fine. Now she has a movie to watch on the flight home today.

Important notes: I first tried copying the movie into iTunes and then into the iPod and strangely enough that doesn't work. It only worked when I copied the movie from the Finder directly to the iPod source list in the iTunes window.

The next time she sync's her iPod the movie will be wiped off her iPod UNLESS we copy the movie to her iTunes on her iMac first!