prosumer camcorders - sony vs canon autofocus
There is no generic difference between one brand and another in terms of the quality of action video you get. The difference is in how you are tracking the action and what the action is.
If you try to shoot tightly cropped shots of athletes bounding about a field, the task is hopeless if you are holding the camera by hand, have no idea what direction the action will take, can't see the LED under the bright sun, or can't see the ball or small details in the tiny EVF. The result will be very shakey and unwatchable, no matter how good or bad the AF.
Generally, camcorder AF is reliable across most better brands, if you have good light and shoot at a relatively wide angle. The results are less reliable if the light levels are low, if you are shooting in zoom, or if the camera's AF gets confused by objects closer to or farther from the one you want in focus. Theoretically, expert manual focus would solve everything, except that good focus is hard to "pull" on the fly in a fast moving, spontaneous event you can't re-take. Focus assist or fringing tools are hard to operate or adjust while the players dash to and fro, in and out of the focus plain. Most action video must, therefore, be shot with relatively deep focus. POV video of sports events or extreme stunts typically uses very wide angle, fixed focus, and zero manual control.