Not being a glutton for punishment, I waited for an identical airing on the Sci-Fi channel to roll around to test the average filters. Unfortunately, "Average" and "Toot" are both very hard to find (broken links). I tried a number of scripts from "7.2.12 Using multiple captures to reduce noise," and the only one I could get to work was "Overlay" (the first one).

It works nicely to reduce noise, but I guess I was hoping for something more. Here's my question: these filters all blend the two captures together; why not identify the similarities between the two (the actual image) and subtract the difference (the noise)? Is there a filter like that? Or am I imagining the impossible?