Tested with 0.3.9.1:

Prelude Text.Feed.Query Text.Feed.Import Control.Applicative> map getItemEnclosure . getFeedItems <$> parseFeedFromFile "podcast.xml"
[Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0),Just ("",Nothing,0)]

The enclosures in the have non-null urls when you look at it. The W3C feed validator says it fails to validate due to a number of silly issues, but does not come up with any problems with its enclosures.