This is a natural consequence of how video compression works.
The images are split up into 8x8 sample blocks which are converted into the frequency domain where you have an average level for the block plus the changes across the whole block, that occur twice, etc.
Periodically a full still frame is sent.
Subsequent frames are encoded with how far different groups of blocks have moved plus the changes.
When there's fast motion or camera pans there are more changes which must be represented and the system starts discarding the high frequencies and small color/intensity changes that make up details.
Cramming more channels into the same system like cable and satellite companies do reduces the bandwidth available to each one so more information needs to be thrown out.
The images are split up into 8x8 sample blocks which are converted into the frequency domain where you have an average level for the block plus the changes across the whole block, that occur twice, etc.
Periodically a full still frame is sent.
Subsequent frames are encoded with how far different groups of blocks have moved plus the changes.
When there's fast motion or camera pans there are more changes which must be represented and the system starts discarding the high frequencies and small color/intensity changes that make up details.
Cramming more channels into the same system like cable and satellite companies do reduces the bandwidth available to each one so more information needs to be thrown out.