Although I doubt I'm the first to have thought of doing this, I came up with the idea so I am not aware of any videos. If I get a bass or guitar in my hands that needs it doing I'll make a short video, however I don't know when that might be as I'm going to try to stop buying basses and guitars for a while and the gibson non-reverse thunderbird I have arriving today comes with rolled edges from the factory.
I think the last one I did was my Squier Classic vibe mustang.
I used a bosch super fine sanding block. This one -> https://amzn.to/46gIM6B
Points to note:
First remove the neck (optional but makes it MUCH easier)
Rub the sanding pad along the edges of the fingerboard so the surface of the pad makes about a 45° angle with the face of the fingerboard.
Use as little pressure as you can and check the results as you go. A little goes a long way so don't overdo it. Feel the edge with your fretting hand in playing position to feel the progress as this is at least as useful as visual inspection.
You're looking to put a small even radius on the edge all the way along the fingerboard rather than a chamfer, so vary the angle of the pad if necessary.
Don't just use one part of the pad, it will eventually get clogged so move to a fresh part of the surface whenever it gets clogged.
After the sanding is complete, wipe the fingerboard with kitchen towel and apply then wipe off lemon oil on the fingerboard as you usually would.
Put the bass back together, string it up and marvel at how comfy it is now on the fretting hand.
Wash the sanding pad and wring it out in water to clear any dust clogging the abrasive — then it'll be ready for next time.