Here is the song they're asking about, from "Minne-Liederen Op Middeleeuwse Teksten (Love Songs on Medieval Texts) by Wouter Paap

Daer was een sneeuwwit vogeltje

There was a snow-white little bird
Sitting on a thorn
Din, don, deine
"Will you, sir, be my messenger?"
"Sir, I will indeed,"
Din, don, deine
He took the letter in his beak
And flew over the fence to his beloved's door
"Are you sleeping, awake, or dead?"
Din don
"Sleeping or waking it does not matter
I've been married half a year already"
Din don
"You're married already a half year?
It seems like a thousand years to me"
Din don
There was a snow-white little bird
Sitting on a thorn

SOURCE: https://digital.library.unt.edu/ark:/67531/metadc79460/m1/173/