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.