Q: I have an iPod Touch 2G and I can't put any videos into it. Please help!

See:

iTunes: Frequently asked questions about viewing and syncing videos

iTunes: May be unable to transfer videos to iPhone, iPad, or iPod

you may have to use a third-party program like the free HandBrake to convert them to a compatible format

• 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

fromn

http://support.apple.com/kb/SP496