The guy in the lab jacket and party hat is either a real burp expert 
or the best casting job I've ever seen.

Paul Hunn is the Burper King. You can tell he's the Burper King because a.) he owns b.) he burps really loud, and c.) the Guinness Book of World Records has officially recognized this as the loudest burp in recorded history.

The odd party you see in the background is the event that Guinness put together for their 2015 book release, which also happens to be their 60th anniversary. Check out the hashtag #gwr60 for more cool record-breaking videos.

Sources: Guinness World Records