In response to Kathryn's comment on my Warro post, I will attempt to explain the link between standard French and Guernesiais. Guernesiais is a variety of Norman French, which comes from Norman, whose roots link back to the Langues d'oïl. Besides Norman, other Langues d'oïl include Gallo, Picard, Chamenois, Lorrain, and Francien (which eventually became modern French during the 17th and 18th century). Norman was the language of the ruling class in England from the 11th to 13th century. So, from what I can gather, Normandy took over England in 1066, and then France took over mainland Normandy in 1204. So, instead of siding with France, Guernsey decided to stay loyal to the British Crown. Britain then granted Guernsey self-governance and many tax privileges. Along the way, French became the official language of Guernsey. This means that French was used in the domains of religion, government, and education. At home and in all other domains, Guernesiais was spoken. So, there was a time in history when everyone was happily bilingual. But - standard French was always seen as superior to Guernesiais and was the 'real' French whereas Guernesiais was known as the 'Patois'.
Near the end of the 20th century, probably about the time radio became popular, English began to filtrate Guernsey homes. Guernsey established trade with Britain, and Guernsey became a popular tourist destination for Brits. Guernsey came to be known for it's lenient tax shelters and offshore banking also became one of the island's main industries. It became very advantageous to know English. English replaced French as the official language of Guernsey in 1926.
So from what I can tell, the Guernsey Norman French has been influenced by Norman, French, and English. What people don't seem to understand is that Guernesiais is not a dialect of French, it just shares the same great-grandfather. Also of note is that many English words are actually of Norman ancestry, such as chair (Guernesiais: tchaire), curtain (Guernesiais: courtaene), garden (Guernesiais: gardin), and castle (Guernesiais: chatel).
I'm not sure about the prosody (rhythm, intonation, stress and other related attributes in speech) of Guernesiais. It has yet to be adequately documented. I agree with Kathryn's comment that the man's speech pattern in the video sounds quite British. His name is Jan Marquis. He is the Language Officer on Guernsey and, as I've read in a BBC article, he is a fluent speaker. And the only other person I've heard speak Guernesiais is the lady in the BBC Learn a Bit of Guernsey French recordings. She seems to carry the same slightly British sounding intonation.