Just a few notes I made watching this vid:
In some states, if you are traveling in a motor vehicle and you have signed a Driver License contract with the state, you are required to show that license on demand, with or without probable cause. In other words, they can in fact demand your ID at a checkpoint. I believe NY is one of those states.
Notice how the deputy asks, "are you a lawyer or something?" It wasn't a wise-ass remark. If he had identified himself as an attorney, that makes him an officer of the court and thereby enjoys certain legal privileges. (Doesn't matter if he is a defense attorney or a prosecutor.)
A K-9 alert is indeed probable cause to search a vehicle, despite the fact that dogs are only about 40% accurate, according to some studies. This "probable cause" is also despite the fact that many K9's are not certified, or their training certs have expired. And of course, a handler can simply train his dog to alert on subtle cues rather than a detection of contraband, drastically lowering the accuracy percentage even further. (Some facts from K9 trainers themselves.)
See more about your checkpoint rights at this link:
What are my Rights at Various “Checkpoints”?