They would also recycle old bits where he was still alive and insert them as new material. Since most of their audience was young they never knew the difference.
No, the producers managed to convince them that Shemp had faked his death as an elaborate April Fool's joke. Larry and Moe were so upset with him that they refused to act with him in most scenes, so they kept sending him to guard the door.
To be fair, based on their previous films, it's not like the guy who edited the video had much basis for thinking they were smart guys.
As a side note, by this time a lot of the Stooges' plans took much longer to execute and they were much more careful. It kind of ruined the whole aesthic to see them carefully swinging bottles at one another's heads.