You can use the Core Media Player TCPMP version 7.1 and above to view iPod videos on your Pocket PC or Windows Mobile device. You will also need the ffmpeg plugin and to hear the audio you will need to download and install AAC decoders from here
iPod video is encoded in a format called H.264 a high compression rate which I believe produces files sizes smaller than that of DivX. The audio is in AAC format. For licensing reasons TCPMP does not support this format as standard. I've installed TCPMP and the AAC decoders on my iPAQ 1945 and was able to watch a film (Crash) with no delays or artifacts and the sound was excellent.
So from one charge of the battery you're looking at 2 hours or more of video playback. With the use of a battery extender you could power your Pocket PC indefinately on a long haul flight.