It does look like it's for power from all the decoupling caps bridging one lead to the ground plane, and the inline diode preventing current from feeding back into the USB port (but allowing the port to feed the power transistor too). The metal cap on the back of the jack blocks us from seeing if that lead runs right into the +5v pin of the USB port.
Considering USB 3.0 wasn't even announced until after that drive was made, you can bet it's USB 2.0 which is fast enough for any DVD drive ever made. However USB 3.0 ports can deliver more power, so what happens if you plug the cable you've got into a blue port?