My immediate response to the prompt of “something to eat” was “rhywbeth i fwyta,” but upon listening more closely to both voices, I’m distinctly hearing i’w, not i. My trusty Modern Welsh Dictionary notes i’w as being a contraction, but I can’t imagine how it fits in this instance, or why it’s not simply i.
Any ideas?
You might think of it as being like “something, for the eating of it”/“for its eating” - the ‘it’ refers back to the ‘something’. But it’s basically just how Welsh does object pronouns - there’s a bit at the end of one of the courses (possibly one of the old ones) where Aran says diolch am fy newis “thank you for choosing me” (to be your teacher), but it kind of works like “for my choosing” in Welsh.
Your ears are working well here! Technically, yup, rhywbeth i’w fwyta, but you’ll often hear rhywbeth i fwyta, so not one to worry about.
The i’w is i + ei, if we’re getting precise about it… 
Yep, that’s what my dictionary tells me. I’w turned up a few challenges ago — darned if I can remember which one or the context — but I do remember that the contraction (i’w = to him, to her, to its, etc, and it took me FOREVER to track down what I was hearing and why) made sense at the time. But I never would have guessed it here.
It appears that i’w turns up primarily after rhywbeth, unrhywbeth, or peth when you’re bwyta-ing (I’m sure there are others, but those are the words I know for now). Odd, though, that it’s i when you have rhywbeth i yfed.
Ah, the caprices of language… 
While I have you here… There’s another bit of ‘Huh?’ that turned up in challenge 23.
In one case, both you and Catrin very clearly say Benwythnos after ch’di. Two sentences later, you’re back to Penwythnos after ch’di (hey, don’t blame me; I’m a musician and I’m absolutely tortured by awareness of sounds 
). So… which is it? Or is this a case of It Really Doesn’t Matter a Whole Lot?
Um, that mainly, certainly… could also depend a bit on the context… 