Comment 11 for bug 798610

Eric B: I think Michael Scherer wrote that the specification of vendor_id:product_id at run time would not work out of the box because the product_id is different on cold boot and on warm boot: it's 8300 on cold boot, and 8501 (8503 in your case) on warm boot (ie: the product id is 8300 when no firware is loaded, 8501(|8502) when the firmware is loaded --- this means the firmware "stays in memory" on reboot, but it doesn't on shutdown, although sometimes, for some reasons, it does on shutdown too, at least here).

Now I'm using 1.6 with a slightly modified version of Michael's patch, and it works for me.
It also tries 8502, so it may work for you too (it tries every isight product ids found on linux usb.ids database).

Anyway, I think we should follow
https://bugs.launchpad.net/isight-firmware-tools/+bug/386812/
since this bug page is (kind of) a duplicate of that one.