“They didn’t want” sounds like “nage nhw’n moyn” but I can’t remember it being introduced….
Is this part of a longer sentence?
Can you point out at what time (minute/second) in the lesson it is, approximately?
Yes it’s part of several sentences at about 11.9
The vocubalary list in that lesson has “they didn’t want - do’n nhw ddim yn moyn”, but ‘that they didn’t want’ is, as you heard, something like ‘nage nhw’n moyn’ which I think really is ‘nag o’n nhw’n moyn’ sounding like nage etc in naturally flowing speech.
There are a few other answers here: