Actually, the original “Adventure’s of Winnie the Pooh” DVD that you may own is made up of three Shorts (or mini movies) that are bridged together. They were not originally shown together as one movie but were shown individually before Disney Feature movies.
It wasn’t until the advent of VHS that they were linked together and packaged as one feature movie.
Yes, I know the films were shorts, that were later put together, along with a 4th short into the film. You can tell the quality drop just from the first 3 and then the 4th, but its still far superior to anything Disney has done with Pooh since.
And no “The Many Adventures of Winnie the Pooh” were not put together strictly for the DVD/VHS, The 3 existing shorts, were put together and a 4th one added and it was released as a Feature film in 1977.