This side of the pond I've heard 509BW using 341.750 fairly regularly for clear comms (not that 'regularly is 'often' over here! last time actually being 25-08-21 when MISTY pair did a flyby at Fairford). Not heard them refer to it as "Black 1 secure" (the daily bear-baiting U2 flight out of FFD uses BLACK1 as it's callsign).
On the topic of live video from airfields in the UK...a couple of civil airports have pretty much 24 hour coverage (I beleive these require subscription access). Military airfields including Heath and Hall tend to be occasional from a small handful of people most of whom also concentrate on civvy stuff except on 'special' occasions (which I guess tends to mean Qatari F15s, ugly fat grey fuel guzzler deliveries and the like). Surprisingly the deployed SJ F15s haven't been enough to have them splooking themselves to rawness. Most of the people doing these occasional video streams seem to use goontube and farceblog and whislt sometimes being reasonable quality film the commentary is unscripted gibberish as though they don't actually know what they are filming.............people lap it up and there's good money to be made (try watching some of the goontube comments from viewers....I wonder how many of them are out of their baby-walkers)!
