You have discovered an interesting issue. This problem seems really to be limited to the situation when you view the iTunes pages of the podcast in the iTunes Client software (I have tested with iTunes 10.3.x Win7 64.). If you click on the play button in the episode list then all episodes with the duration of 0:01 getting played only for 1 second.
I guess that this problem may be solved by inserting the correct duration for each episode. But I’m not sure whether the iTunes page updates these values while the publication dates and the GUIDs of the posts remain the same. That is why this may help only to avoid this problem for future episodes.
In your case the duration value of the episodes 1, 2 and 3 is 0:00:01 in the feed. This means that the duration field in the podPress box below the post editor in WP was left empty or filled with invalid characters or with an equivalent to this duration.
Please, control the duration values of these three episodes and correct them if necessary.
(In some of the past versions of podPress existed a problem with this input field (see this thread). But it is fixed, now.)
Setting the duration value to the correct value should fix this problem.
Regards,
Tim
