It's been a while since I've played any of this, and it is a very different sort of music--so I'm not sure how much help I can give, but--the melodies seem superficially quick and fairly simple, but the accent patterns can change from one phrase to another, and there should be a slow, but driving march feel underneath.

There is a lot of repetition, but it never sounds repetitious, because each player tends to have their own feel and ornamentations, and their is a polyrythmic quality that plays off between the quick feel of the melody and the underlying beat, so the ear tends to hear a changing blend of the elements.

Basically, your best bet is to listen to the YouTube clips repeatedly, especially the ones with dancing and try to get the feel first, and work out fine points of melody after--And thanks Mr. Happy for posting those--it hadn't occurred to me to look for any of that in YouTube, and I love it! Breton music is a real, living tradition, and a way cool one, at that--have fun with it, Dazbo!