...meant nothing more to me than "some of the men Dad works with, and their children, some of my classmates." The burning of Rovaniemi having been presented as "Als Dank für nicht bewiesene Waffenbrüderschaft"(*), and all that, were things I learned of only years later.

Here's a (very) loose translation of the refrain:

The ghetto of Warsaw
Surrounded by the Wehrmacht
to whom you never are
imposing, gun in hand
around you Joe Schmoes(?) and Fritzes(?)
and on top of that the Focke-Wulfs
takes a new kind of courage
comparing blood to water like this,
so forwards it is.

i.e, it seems to be in praise of the uprising in the Warsaw ghetto, mainly on the grounds of admiring the sheer chutzpah (heh) -- or should that be sisu? -- of it. I think.

I'm particularly proud of the last two lines; at least they rhyme.

[Edit:] Oh yeah, almost forgot: Here https://www.youtube....tch?v=zz2N5y225D8 is a link to a better-quality copy of the same video.

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(*): "In thanks for brotherhood-in-arms disproven"