Basically why the Norwegians don't like the Swedes .
But as Norwegians give out peace prizes etc., remember that Nobel was in fact Swedish and resposible for being the inventor of dynamite. Nobel also owned Bofors ( Gun ) which was largely produced in Sweden.
It's nice to remain neutral in wars whilst supplying all the guns and ammunition to the protaganists. Nice people.
The Swedes are disliked ( I almost was going to say hated ) by Norwegians purely because the Swedes in their neutrality, allowed Hitler to enter Scandinavia unopposed in Hitler's quest for the heavy water ( deuterium oxide ), required to produce nuclear weapons.
In April 1940 the Norwegians were still neutral and also infamously gave birth to another word in the English language - Quisling.
The "song" above for me only miniscule historical merit and should be confined to the dustbin of history as a piece of over-educated poppycock.