Ah.. those are .avi container files encoded with xvid video codec and mpeg audio (mp3?) codec. I expected that should work in the built-in media player but it doesn't.

But here's the thing! It's video.. and you only need to change the default VIDEO player in gPodder.

Here's how! Press the MENU key (or tap the drop-down menu on the top-left corner of the gPodder window). Go to "Podcasts", then choose "Preferences". Tap "Advanced..." and in the "Search for:' bar, type "player". Scroll down and be sure to put a check mark next to "maemo_allow_custom_player" then scroll down some more to the very bottom and look for the entry labeled "videoplayer". Tap on the right side, where you can enter in the path to the video player, and put in "/usr/bin/mplayer" (be sure to hit the ENTER key to enter it in when you're done... hitting CLOSE right away won't enter it in).

Once you've done that, hit the CLOSE button and give it another go. You'll notice that the video will play just fine from gPodder and your audio (mp3, ogg, etc.) will continue to play with the system default player.

If you ever decide you want to use another player for audio, you can change the value in the advanced preferences for the "player" (not "videoplayer") to whatever you prefer to use (I, for example, use /usr/bin/panucci now) and your VIDEO podcasts will still use /usr/bin/mplayer.

Let me know if this worked for you or if you're running into something else.