A lot of these programs I've never heard of, but the methodology seems sound and the results consistent with other reviews and tests I've seen.
I know it's a big disappointment for fans of Avast!, but it's not the best at detecting viruses.
I can confirm this from my own experience: I was cleaning a computer which had been connected to the internet with XP SP1, no anti-virus and no firewall. As you might imagine, it had just about every virus, Trojan, worm and spyware program ever written on it.
I cleaned it with Avast!, Trend Micro Sysclean and TDS-3 and they all found heaps of malware, but a worm remained in memory which non could shift. The removal tool for that worm from F-Secure couldn't remove it either.
Finally I downloaded Kaspersky and it removed that worm and a couple of other Trojans.
Of course that's not the whole story: on an up-to-date system with a firewall, Avast! provides good protection. I use it myself. Kaspersky is also very expensive.
However, in terms of detection rate, I'm not surprised it's No 1.