This morning I tried to watch some of my downloaded TV shows on my video iPod whilst on the train to London. After about 20-30 seconds the playback would freeze for a couple of seconds then resume without any sound. This happened on every TV show I tried but video podcasts were fine. A bit of Googling once I reached the office shows that this is a known bug with version 1.1 of the firmware. This site has a procedure for downgrading your firmware without needing to reformat your iPod. I’ll be trying it as soon as I get home.
Update: The downgrade procedure at http://www.ipodbank.com/showthread.php?t=143 worked perfectly. I’m back on the original firmware without needing to wipe my data and I no longer have the video playback issue.