Ipod touch - MPEG-4

First drag your files into iTunes.

They should show up in the "Movies" section of your library.

Now plug in your ipod and try syncing the movies. If they sync, then you're all good.

If there's an error message, select all your videos and go to the "advanced" menu item.

Choose "Create iPod of iPhone Version" this will convert your videos to the proper format.

When the conversion is done, resync the videos to your iPod.

-Ben

Tech specs:

• H.264 video up to 720p, 30 frames per second, Main Profile level 3.1 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
• MPEG-4 video up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
• Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in .avi file format
• Support for 1024 by 768 pixels with Apple VGA Adapter; 576p and 480p with Apple Component AV Cable; 576i and 480i with Apple Composite AV Cable (cables sold separately)

Also see:

iTunes: Frequently asked questions about viewing and syncing videos

Verifying iTunes video conversion and video syncing using sample Q...