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
You don’t know much about snakes, do you?