i have never seen a miniDV camera without a FW port (also called IEEE 1394), it usually has a cover of some sort over it, and may not be in the same location as the AV composite outs.
USB is too slow for video transfer. It is only for still photos off the memory card.
and the USB/FW hub, im sure its just a port replicator ( turns 1 or 2 USB and 1 or 2 FW ports to 4-6 USB and/or 2-4 FW ports.) so technically its not switching USB to FW, just adding more of each (on seperate busses), so no that would not work.
If your camera REALLY doesnt have a FW (IEEE1394) then im guessing its a Hi-8 or VHS-C/ in which case you will need a converter box (analog to FW) OR a slave deck (a VCR to play your Hi-8 or VHS-C sized tapes with a FW out-which is gonna be pricey to say the least).