Hi all,
I by no means a flash guru but here are my findings on Camtasia and Flash.
I also use Camtasia for developing training material on software processes and found that recording at 640x480. I don't change the screen res, I size the window to 640x480 then record. When you compile the flash output in Camtasia leaving the size as the original, I found, greatly reduces the size of the flash file.
Patrick