I.R. Leak Detection - Does Anyone Understand How This Works?

DRSMPS wrote:
... What is the technology here? Will water stay cooler while the remaining portion of the roof heats up in the sun?

You got it. We had it done to our building a few years ago. Found the weak spot was not where the water was dripping into the ceiling. The bad spot was maybe 25 feet away and the water traveled untill it found a weak spot in the wood.

A consumer grade IR detector would not do the job. The special camera used to view the roof probably cost more than the cost of having a RV roof rebuilt.