Focus On The MPEG-4 Fast Motion Codec
This sequence (720 x 416 pixels) was created with the fast motion codec with an average data rate of 1500 kBit/s (maximum 6000 kBit/s). Still the overall average data rate is extremely low at 145 kB/s.
Here the same sequence (720 x 416 pixels) can be seen with a very low (average) data rate of 250 kBit/s. You can still make out a lot of details.