Add https://8mb.video/ to the list - it does exactly what it says on the tin (and while it doesn't explicitly mention it, its broader purpose is to compress videos down to Discord's file size limit)
Thank you! I've spent far too much time in HandBrake when I could've been using this. You have improved my life
Is it? It would still absorb energy upon impact. Which, in contrast to popular belief about bike helmets, is its main function. Yes, ordinary bike helmets will also just break. But in doing so, they absorb energy which then won't be absorbed by your skull.
There is no point in a perfectly stiff helmet. It would just transfer the energy right through and you'd crash your skull into the helmet, which doesn't help.