There is a rough calculation that shows that at such a concert the odds of being on the kiss cam is roughly 1 in 22,000
However, taking into account their highly visible private box location and their overtly "lovey-dovey" behavior, their specific odds of being selected for the Kiss Cam were far better than the general 1 in 22,000.
A more realistic estimate for their particular situation could be in the range of 1 in 50 to 1 in 100
FAFO !