Does anyone know why it sounds like they're singing "bheireadh gu leor" instead of "theireadh gu leor?"

I heard in other spots what sounded like "thubh" instead of "thu"...is it possible it's "Saoil a Mhor am pos thubh__theireadh gu leor....?"

Thanks so much for any help!!

Sile Shigley
shigley@gmail.com