USB is well, that's been discussed for years so unless this is a web cam or the camcorder offers such then the answer is the same as before.
Today you might look at HDMI and that Black Magic HDMI capture card.
I know with a FireWire camcorder you can use video capture software to stream the files to your hard drive while you are actually recording.
Are there any other options out there that would allow for the same via a USB connection? If so, I haven't been able to word it correctly in my many many searches.
I want to record video and have the video stored on computer or drive during the time I am actually live recording the video.