The quality of video on most digital cameras sucks; the physical dimensions of the video are usually somewhere between 320 by 240 pixels up to 640 by 480 pixels, whereas 'real' video is 720 by 576 pixels. Most digital cameras also shoot at 15 frames per second (more expensive models go up to 30fps) which is too jumpy for smooth playback. Also the video file format they record in can be awkward to edit in the popular video editors.

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Better than a poke in the eye with a pointy stick any day...