my cousin's PS2 is modded, i guess with magic3 modchip.
and yaa i have tried both these ways but still no luck--
1)Booting directly from USB Advance disc, as in the video attached.
2)booting through FMCB i.e. FMCB->ulaunch->USBADVANCE(stored on my USB drive)
well i really out of idea but when you get that please wait is your memory card plugged ? if yes try to unplug it and select a game again .i don't why i said that by try out .
edited : after looked at your video its seems you installed only one game maybe that game is incompatible or its your usb is not compatible ?
test another usb drive