I am enclosing my raspberry pi B+ into a camera case due to which the micro USB power plug on the pi is not accessible, I was thinking of powering it through the normal USB port. https://www.youtube.com/watch?v=lGELwCXeNTs this shows powering a raspberry pi B through a USB port. Not sure how to do this for my raspberry pi B+. I have tried powering it through USB port but the didnt boot up. Is there any other way?