The iPod 5G (firmware 1.2) and iPhone officially support the following video formats:
H.264 video, up to 1.5 Mbps, 640 by 480 pixels, 30 frames per second, Low-Complexity version of the H.264 Baseline Profile with AAC-LC audio up to 160 Kbps, 48 kHz, stereo audio in .m4v, .mp4, and .mov file formats
H.264 video, up to 768 Kbps, 320 by 240 pixels, 30 frames per second, Baseline Profile up to Level 1.3 with AAC-LC audio up to 160 Kbps, 48 kHz, 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, 48 kHz, stereo audio in .m4v, .mp4, and .mov file formats
The iPod classic/Nano 3G/touch officially support the following video formats:
H.264 video, up to 1.5 Mbps, 640 by 480 pixels, 30 frames per second, Low-Complexity version of the H.264 Baseline Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
H.264 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Baseline Profile up to Level 3.0 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, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
However, information pulled from an iPod Classic with firmware 1.1.2 indicates it supports:
H.264 video, up to 5.0 Mbps, 640 by 480 pixels, 30 frames per second, Low-Complexity version of the H.264 Baseline Profile with AAC-LC audio up to 256 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
H.264 video, up to 5.0 Mbps, 720 by 576 pixels (but 10368000 maximum pixels per second), 30 frames per second, Baseline Profile up to Level 3.0 with AAC-LC audio up to 256 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
MPEG-4 video, up to 5.0 Mbps, 720 by 576 pixels (but 307200 maximum pixels), 30 frames per second, Simple Profile with AAC-LC audio up to 256 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
foo_dop will only accept video in an MP4 container. Programs that can convert video into the required format include: