I've had the most unfortunate opportunity to own an hdmi video capturing device called the elgato HD60, the cheapest hdmi capture device money can buy, designed for gamers, with a software interface that I suppose makes sense to gamers, but certainly not to me.
But, the thing I really learned in using this device is that some USB devices require more power than others. This lovely POS elgato device was designed to work perfectly well with the included USB cable, with it's power requirements, and nothing more. So when I went to their tech support department with all my problems trying to use it over a 25 ft. usb extension cable and hub, they replied back with power requirements. I replied back with some specs from the devices I was using that showed they should work within those power levels, but....eh...I forget the comeback to that one, but at some point I got the tech to admit that, connecting a powered usb hub to the end of my extension cable, and plugging the elgato directly into that powered hub, would in theory provide it the power it needs, while offering several disclaimers that this is not a recommended or supported method of using the device.
BOOM! Device works now. Still with it's awful limitations and nonsensical software interface.
TLDR: if you have problems with USB hubs or extension cables, use a powered USB hub.