For some reason, such as reformatting hard drive, switching Mac computers, you may have to sync your iPod with a new iTunes. Worried that iTunes might erase the existing content on iPod?
iTunes doesn't let you transfer iPod to iTunes for Mac directly, you need to the help of third party. In so many software, I nominate iPod to Mac Transfer to you that is iPod to iTunes transfer for Mac. It can transfer all iPod content to iTunes on different Mac, for example music, movies, playlists, videos, podcasts, photos, music, TV program and stuff.
Note: For Windows user, You can use the iPod to Computer Transfer to copy iPod to iTunes.
Step 1: Connect iPod to Mac
Run this iPod to iTunes transfer for Mac software, and connect your iPod to your Mac computer via USB cable and the program can recognise it automatically.
Step 2: Select the files that you want to copy
Open the library/playlist that you want to export files, and then check the file(s) you want to export in the file list.
Step 3: Copy iPod to iTunes on Mac
Click the "Export" button to transfer all the files in your iPod to Mac directly, this task only needs a few seconds. Then you only only drag the transferred files to your iTunes library on Mac to backup iPod to iTunes for Mac.