Why is it "diod" and not "ddiod" as we saw in the picture questions? EDIT: Is "ddiod" just the soft mutation form?
Yes it's the soft mutation, which I assume only affects the word directly following it. Here 'diod' comes after 'a(c)' which I think takes aspirate mutation
Audio seems to have problems pronouncing Welsh words that are written separately but pronounced as one word, e.g. Ga i