Power consumption is about 5W (1A from USB would need 2 ports) and that is going to suck run time. If you need full portable, try and find one with a Battery or power adapter.
Use a Juice box on the power only USB connection and Isolate the +5 lead ONLY on the main USB to prevent back feed issues
I use a USB dongle (aluratek) with a old LCD Monitor (the monitor has its own power) with good results for up to low res video