Okanogan: I doubt very seriously it was a "Boomer" tip thief - MUCH more likely a co-worker (busboy, drug influenced co-waitress etc etc etc) or observant opportunist customer!
Be sure and let us know what the video confirms.
Sorry the sons holiday surprise was spoil't!
I always make sure the waitress gets handed the bill - the money for the bill and the tip.
NEVER leave money out ANYWHERE in this day and age where it can simply be "picked up and walked away with"!
Hold into the wind
VarmintGuy