Here's the link
Knots of May Garland Day
One of the band members playing for the Garland dancers is playing a black triple S curved thing with a long brass connect and mouthpiece. He uses both hands to finger what are evidently holes in the barrel and it produces a tuba like sound. Could it possibly be a ram's horn? I've never seen one close to that shape.
It first appears about 1:04 into the video and can be seen clearly by 1:10.
Blessings
Barbara