You need to control camera movement very carefully when you're shooting video. For static subjects and framing you can simply mount the camera on a tripod, but if you need to move the camera to follow a moving subject, you need to keep the camera movement as smooth as possible – you want viewers to pay attention to what the subject's doing, and any camera wobbles, shakes or jitters will be really distracting.
It's not possible to hand-hold cameras and get smooth movement, so videographers use a variety of 'rigs' and braces to keep the camera steady. Some use chest or shoulder braces, others use complex counterweights and specially-balanced frames. A pro rig will also help alter focus smoothly while filming – 'focus pulling'. Geared focus mechanisms make this smoother still, and there's a new breed of specially-designed 'cinema' lenses from makers like Samyang and Canon.
You won't get perfect results straight away. Rigs initially feel odd and awkward to use, and it takes a good deal of practice before you start to see any benefits.
Camera stabilization systems can be a useful alternative for 'run and gun' videography, where you're chasing a moving subject while filming. Olympus has attracted a lot of attention with the OM-D E-M5 II, which has a five-axis sensor-shift stabilization system that works in both stills and video mode.
