The video bitrate is one of the key measures of likely video quality. It's the rate at which the video data is recorded in Mbits/sec (megabits per second). Cheaper consumer cameras may offer the same video resolutions and frame rates as professional models, but much lower bitrates.
This means the video is being compressed more heavily and the quality will be reduced – and this is often visible in the way motion is rendered and in the quality of details and textures.
The nearest analogy for stills photographers is the camera's JPEG quality setting. A low bitrate is like being restricted to 'Basic' JPEG quality when you'd really rather use 'Fine'.
Video codecs are changing and improving all the time. A better codec will produce better quality at the same bitrate. With that in mind, these are just broad guidelines about bitrate and video quality:
25Mbits/sec: OK for consumer use but the difference in quality will be visible to experts
50Mbits/sec: Much better. Fine for most light commercial/professional use
100Mbits/sec plus: Required for demanding, high-quality work, especially for better chroma subsampling or intra-frame compression.
