Fremantle does ContentID matching on nearly all of the fan uploads of their content onto Youtube. They get ad revenue, the videos stay up, everyone wins.
They've, within the past couple of weeks, switched the overwhelming majority of episodes from September 1982 to the end of April 1983 from Monetized to Blocked (at least in the US), and for their to suddenly cut off revenue from such a specific block of content, at least IMO, gives me a reasonable first guess as to the episodes currently in Pluto's rotation (outside of stunts and specials).
Also fits Fremantle's MO of starting with a smaller block of transferred content then adding to (and subtracting from) the rotation over time.