Default [Q] Connect dslr and portable hdd?

i just ordered a OTG able with usb power ( is it possible to connect my dslr to one, portable drive to the other plug and use my nexus 7 to transfer files from the camera to the drive or would i have to copy them from the camera to the nexus and then the drive. if it works for the camera, woul dit work for a camcorder where the files are significantly larger?
Sprint SGS5, Nexus 7, Sprint SGSIII, Samsung Captivate