A77 Poor low light Video compared to Nikon and Canon?

There's nothing wrong with the camera settings or the camera itself. The minimum shutter speed for your shot to be useful is 1/50s for 24fps, go slower and be prepared for some nasty motion blur. It's called the 180degree shutter rule. This rule applies to ALL cameras, be it a Sony a77, Nikon d5100, or a $25,000 Canon c500 cine cam.