Ooh, I love being technically correct :) So here goes:
there were 213 critters that went down AFTER the total had dropped by 5000. Surely this couldn't be done in a mere 3 minutes (at an average rate of 41.6667 per minute, only 167 could be killed in the max of 4 minutes countable (ie. start of one minute for one post, very last second of the minute for the other post, unless the rate for the last 4 minutes was 30% over the 2 hour average, which I suppose is quite possible)... therefore, there were 5000 beasties down in less than 2 hours, though possibly not (if the last couple minutes were crazy).
As a different point, perhaps Thomast waited a little bit before posting, so that what he actually meant was 5213 beasties down in less than 2 hours (if he waited 3 minutes before posting, or if there was a lag large enough).
hmm, so with this, I guess we'll never know who's right... but I hereby give myself nitpicky points, redeemable at any engineering (or math-related) business.
That was fun...