"What do you think about rugby?"
Translation:Beth wyt ti'n feddwl o rygbi?
Well spotted. We were hoping to get away with this one.
It's because the full sentence is 'Beth dych chi'n Ei feddwl o Rygbi? (Lit:- What do you think It about Rugby) - capitals only for emphasis here.
The pronoun 'it' refers back to the interrogative 'What' at the beginning of the sentence.
But in speech the 'it' is dropped.
In a real life conversation it would be difficult to distinguish between 'feddwl' and 'meddwl' here so I never point it out to my Welsh classes.