Especially terrifying, in modern light, to watch Jimmy Saville narrate child safety videos.

For sheer shock value, little can beat the texting-while-driving one. No direct link but you can google "british texting while driving ad". The NZ safe driving ads are also really something. "new zealand safe driving shock ads" brings up one that really triggers, but then again, both the above particularly work if you're a parent.

I assume https://www.youtube.com/watch?v=R0LCmStIw9E is the one you are thinking of (there was a shorter version that aired in TV ad breaks).

The Think! campaign was always pretty on-the-nose, as you need to be sometimes to get these messages across. The seatbelt and in-town speed limit ones stick in the mind too: https://www.youtube.com/watch?v=mKHY69AFstE and https://www.youtube.com/watch?v=jDpOAXfangI respectively.

The memorably stark tone and the frequency they were on TV made these spots ripe for parody, for example this one from Monkey Dust: https://www.youtube.com/watch?v=PsOk9Ln1qOY

I really like this PSA from the British THINK!, juxtaposing celebration and darkness: https://www.youtube.com/watch?v=CERT0xNFGo4

Wow, that first one is genuinely horrific, I can’t believe they had the guts to release something so strong. Glad they did though, it probably saved a ton of lives.

I'm partial to this Irish one: https://www.youtube.com/watch?v=LNL6t-Eu-IY

For shock value, the Canadian workplace safety ad featuring the chef comes pretty close: https://www.youtube.com/watch?v=noFCekWiUGE

The New Zealand ACC public safety advertising campaign was gold.

My favourite is the one at 1min 30 but all are complete classics here.

https://m.youtube.com/watch?time_continue=105&v=9ciomPP8MyE&...

This terrified me for decades after seeing on tea-time TV: http://www.weirdretro.org.uk/the-finishing-line-the-banned-p...

In France, during the late 90ies/early 00ies, we got a bunch of "quite direct" Road Safety ads.

The one that traumatized me the most as a child was:

https://www.youtube.com/watch?v=gpNMrcgiAdw