Took a two-and-a-half minute video of the sun setting, to see how well the P300’s video continuous focus works. See the results below.
The bottom line is that it works well, as long as it has something to focus on.
At 1:20 into the clip it gets too dark and there’s nothing in the frame for the focus to lock on, so it’s a blur until 2:00, when the sun was almost gone and I zoomed out to let some people into the frame.
Another thing to notice is that the zooming of the lens can’t be heard in the video. You can hear a click or two of my fiddling with the camera buttons, but other than that it’s all wind and waves (so if you’re looking for a camera with a good wind-cut function, keep looking).
In general, this is not a bad result for the P300’s video continuous autofocus, as much as it is a lesson on how to shoot videos. You must always make sure you have enough contrasty elements in your frame. Objects with edges, distinct colors, something to help your camera focus.