Thanks for that suggestion, which I have just finished studying. Unfortunately, I get the impression that this would not be as quick and easy to use as the scene detection systems in consumer editors, which will also deal with imported files.
I was hoping to get away from the need to run two editing systems and upgrade to Premiere Pro CS5.5 for everything and use the Matrox MX02 mini for the interface. I thought the MX02 mini would definitely have optical/content scene detection, as it is designed to include analogue capture. But I cannot find any reference to it in the user manual.
It seems ironic that my old semi-pro Pinnacle DV500/Prem Pro 6 set up, that I still use for analogue capture, had these scene detection facilities in 2002, which are still not standard features on pro editors now.