To view podcast on TCPMP, you need AVC plugin for H.264 video and AAC plugin for audio. These two plugins are not part of the TCPMP package. I found this post with a link to a cab file of these plugins. I tested these plugins with TCPMP 0.72RC1. It runs great most of the time except there are some dropped frames at times.
I extracted the cab file and zipped the plugin files. You can download the zip file here. Just unzip the file and put the plugin files (avc.plg and aac.plg) in the same directory of TCPMP (player.exe). If you use my Mio C230 unlock pack, put them in the Script directory (Mio Device) F:Script.