Every time I've tried to search Youtube for this, I've come up with either the famous PIF where a camera is slowly gliding through a burnt-out house with dubbed on shrieks, or the other one where a kid ends up burning down his home because he was too careless lighting the fire in the living room and was more interested in reading the Dandy or whatever. This isn't either of those. Instead, this is something that I saw once, and only once, during the always-unsaleable ad-break time of around about 5:45 am during an edition of the ITN Early Morning News in 1996.
The PIF began with two kids playing with matches in a blacked-out room – I think they were meant to be sister and brother. The older girl inevitably dropped one and a conflagration started. Which was nasty enough, but then the soundtrack went insane, ultra-heavy delay being applied to the girl screaming "MUM, MUM, MUM, MUM, MUM -" and then there was a massive film splice and the sound cut out and the action froze, the girl's face remaining on screen mid-scream.
No word of a lie, my blood genuinely ran cold. I was rooted to the spot with fear. I have never been so glad as I was when it was faded out and part 2 of the bulletin began. The fact that there seems to be absolutely no mention of this PIF anywhere on the net, and all my searches for "PIF matches kids fire" or variations thereof all come up with the other two PIFs I mentioned earlier, makes me wonder if it was actually some terrifying broadcast from another dimension that only I could see.
UNK SEZ: Chris, I think I may have found it! I just googled "playing with matches PSA" looking for an image to illustrate your NTT and it popped up! Can this really be it? It seems so much like what you described….