Probably related to the fine folks at Eugene Lambert's Puppet Theatre (though the theatre is in Monkstown, County Dublin). Lambert (1928 – 22 February 2010) had a giant named Murphy.

Then again, it might be a coincidence, and it might just be a creation of Worhouse Art Studios and their carnival arts group. (Their site is linked from the YouTube video uploader's profile - I'm intrigued enough that I asked them, and I'll pass any info I get.)

... Lambert was from County Sligo, so I thought it might be a tribute to him. But his puppets might be more of the hand-puppet sort, and my quick internet search simply aligned "giant puppet" and "County Sligo" with Lambert.