The audio accompanying this piece is from a track titled  Kai-ja-met-tra (Mercy) from Wisit Sasanatieng's 2007 film, Fah Talai Jone (Tears of the Black Tiger). It is a 1940s Sunthraporn big band number, composed by Leud Prasomsap and Eua Sunthornsanan and sung in the film by Veera Bamrungsri. The Phra Rahu series, like Sasanatieng’s film is, ultimately, a paean to almighty Buddha for his compassion​. ​
 

Yoo hoo hoo hoo

I've been crying for your mercy

Does anyone have some mercy for me

Yoo hoo hoo hoo

From the lyrics of Mercy by Leud Prasomsap

(as translated in the subtitles of Tears of the Black Tiger DVD)