Apparently you didn’t look at all his photos. Neither snake you show in your photos is a pit viper, the snake in his photos is definitely a pit viper. Probably a moccasin.
Ding ding ding!!! We have a winner. It is without a doubt a pit viper. It’s very clear in his photos.
What makes you think it's a pit viper? Can you make out either of the two heat-sensing organs located between the eyes and nostrils in those distant shots? Or the "movable fangs"?
Pit Viper:
Any species of viper (subfamily Crotalinae) that has, in addition to two movable fangs, a heat-sensitive pit organ between each eye and nostril which together help it accurately aim its strike at its warm-blooded prey. Pit vipers are found from deserts to rain forests, primarily in the New World. They may be terrestrial, arboreal, or aquatic. Some species lay eggs; others produce live young. See also bushmaster, copperhead, fer-de-lance, moccasin, rattlesnake.
"pit viper." Encyclopædia Britannica Online 2009:
http://www.britannica.com/EBchecked/topic/461927/pit-viper
The 2nd photo I posted was of a "Cottonmouth". The first one, I see now, was way off.
How to Spot a Cottonmouth Snake:
The Cottonmouth is the only poisonous water snake found in North America. It is a pit viper and senses movement with its pit in between its eyes. The Cottonmouth snake is found in three subspecies. The Western Cottonmouth, the Eastern Cottonmouth, and the Florida Cottonmouth have common characteristics and traits that distinguish them from nonvenomous water snakes.