I sew. I said exactly this sentence once to my Norwegian friend. She said "do not say that again, unless you include 'for å sy'. Or you really mean drugs."
I wouldn't say "fabric" for this meaning. There's also surstoff (oxygen) and other expressions where stoff means rather something like "material", or "element".
Since we're talking about slang, older German action movies have "Gib Stoff!" (Give stuff) for "accelerate, the bad guys are coming!".
Curious, it looks like "stuff", I'd like to know if this sentence may be more... usable...
I might add that the lady says med clearly in the slow playback of the listening exercise...isnt this incorrect??
What you're probably hearing is the difference between how English speakers pronounce R's and how Norwegian speakers pronounce R's. In English we have what we'd call a Common R (postalveolar approximant) but in Norwegian (at least the dialect the Duo voice uses) I believe it's a Tapped R (alveolar flap) or a Rolled R (alveolar trill), which is somewhat similar to the D sound because the tongue hits the same part of your mouth. In fact one way of practicing this kind of R sound is to start by substituting R's with D's and working from there.