Yes, the house code is set to A1 and the VT38A responds to the A1 signal being sent to it. But that still does explain what code the VT38A sends to the VCR Commander II or even if it is a X10 signal??
I believe that's the flood cams I have. If yours is set to A1, the motion sensor should be transmitting an "A1 ON" signal when triggered. After checking to make sure that house code is set to transceive in AHP, as roger1818 said, set up your macro as A1. Also note that the VCR Commander II manages cameras in blocks of 4 using X10 codes 1-4, 5-8, 9-12 or 13-16. It turns off the other 3 when one is turned on. eg. If your camera is set as A1, when it sends an "A1 ON" signal the VCR Commander sends "A2 OFF", "A3 OFF" and "A4 OFF".
I believe there is a bit of setup for this to happen but don't recall it being hard. It's been years since I set mine up and I'm a bit fuzzy on the details.
As a side note, many of us long term X10 users avoid the A house code as many battery sensors default to A1 when their batteries become low.