Hey Fred, welcome to the forums!
Thanks for posting.
I suspect it is a land animal of some kind, (though I'm not sure what kind). It looks as if it is barely able to keep its head above water in quite a bit of that footage, which indicates to me it is exhausted.
You will also note it seems to be heading directly to land, and the footage remarkably finishes almost at the point where if it WAS some kind of quadruped, it might be able to get a foot on the lake bottom, start to stand up rather than swim, and then proceed to wade ashore. If the filmer actually thought it was Champ, I would think he/she would keep filming and post the end of the footage too, but that doesn't seem to be the case.
In short, I believe it's just someone trying to get YouTube views up. You will also notice they removed the ability for viewers to comment on the footage - I wonder why?
Some info about Champ:
"The first reported sighting actually came in 1883 when Sheriff Nathan H. Mooney claimed that he had seen a “…gigantic water serpent about 50 yards away” from where he was on the shore. He claimed that he was so close that he could see “round white spots inside its mouth” and that “the creature appeared to be about 25 to 30 feet in length”. Mooney’s sighting led to many eyewitnesses coming forward with their own accounts of Champ sightings. Mooney’s story predated the public Loch Ness controversy by 50 years."
"Champ reportedly can be seen in a video taken by fishermen Dick Affolter and his stepson Pete Bodette in the summer of 2005.
http://tinyurl.com/negdm4
One piece of evidence, though not a "sighting" per se, is the recording of echolocation from within the lake by the Fauna Communications Research Institute in 2003, working as part of a Discovery Channel program. The group has concluded that the sounds they have recorded are similar to that of a Beluga Whale or perhaps an Orca, but not of a known animal, and no dolphin or whale species have been previously known to live in the lake. Study of the Mansi Photo in this context has led to speculation that rather than a neck and head, the photo shows a flipper of some large animal in the act of rolling."
Source:
http://en.wikipedia.org/wiki/Champ_(legend)
Cryptomundo has some more research to offer here:
http://www.cryptomundo.com/cryptozoo-news/oslen1wkd/
Some folks believe it to be a hoax, with a diver or someone pushing something through the water.... hmmm....
Kind regards,
Shazzoir