Hi everyone 
does anyone know why sculpt collision doesn’t work when I’m doing hair?
What I mean is that this exact function from the video You sent doesn’t work 
I have no idea why
try to reset your settings to default ones.
Or just re-install your Blender. Or try another version, 3.5 for example
In the video author shows it in Blender 3.4 and then 3.5, try those versions
It should work though
Try to increase your Strength to more higher value such as 3 or 5!
it works fine in 3.6, I have just tested it. Inrease the strength of your Comb tool to something like 3, 5 or higher
Cheers
i tested it on simple subdiivided cube and it works but not on my project. I made human head and separated part of it to add hair. And collision does’t work on that part ://
May you share your blend file?