Research: Back to the Roots, but how?

Since some time, I meet media phenomenoms, I remarked in my youth, met again today, but can't classify or find out by internet research. But these things are sometimes linked with happenings today like: Song of the Hot Dogs (Bavarian Dixie Band): Die Moritat vom Hintertupfer Bene ... and ... The funeral of Queen Elizabeth II. (starts at about 13:25, the same melody) How can I find out the origin of this melody? To find out is tough, if you don't know the origin.