Ellen Marsden, a biology professor at the University of Vermont, agreed with Nickell, telling the Burlington Free Press she thinks the animal could be a young moose in distress.
Olsen admits he doesn't know what it was.
Tracked down by a reporter for the Free Press, he told the paper, "It struck me as something that was long (and) that it didn't have much girth."
The Free Press contacted its own consulting cryptozoologist, Loren Coleman of Portland, Maine, who said a laboratory analysis would be necessary.
"The film needs to have a formal forensic analysis performed, to break it down frame by frame. It needs to be looked at very seriously."
Cryptozoology is the study of legendary or mythical creatures.
Since the Vermont-based Champ Quest group became inactive a few years ago, there has been no central clearinghouse for Champ sightings.
Last summer, there were few reported sightings of the legendary lake monster.
Its first sighting was in 1609 by French explorer Samuel de Champlain, who noted in his diary that he had seen a "sea serpent."
Hundreds of Champ sightings on Lake Champlain have been reported over the years, most from Bulwagga Bay in Port Henry and Button Bay near Vergennes, Vt.
Former Champ Quest Director Dennis Hall had shot video of a large creature swimming in Button Bay.
The most famous Champ photo was taken in 1977 by Sandra Mansi, now of Bristol, Vt. That photo of a long-necked creature was published in the New York Times.
Many people believe Champ is a large sturgeon, while others think it is a genuine prehistoric throwback, maybe a plesiosaur.
Whatever the animal was that Olsen saw, he told the Free Press that he never saw it leave the water.
He said he stopped filming after two minutes because his cell phone was running out of memory.
E-mail Lohr McKinstry at: firstname.lastname@example.org