The developer, Jackson Myers, after getting more details of the problem from me, sent a newer version to test. It fixed the problem I was having, and he'll release it as version 3.2
I'm raising the overall rating to 4 stars. I misses the 5-th star only because the configuration options on the back pane (and the UI*) aren't as self-explanatory as they could be, and "Reset Preferences" gives no warning that you'll lose all the URLs you've added to the list of webcams.
* For example, did you know that left- and right-arrow will advance the image to the previous/next camera on your list? I haven't seen it documented anywhere and only discovered it by chance!