Here are a couple of still shots showing the mangling of the grain pattern by the MPEG encoding. This is from the first short on disc 2 of Volume 1 (Czechoslovakia On Parade, 1938).
You can see grain effects as MPEG artifacts in the map frame, which has few edges to use up the available bits. The city scene is much busier, and apparently there are few bits left to try reproducing the grain at all once most are used to reproduce edges.
