This. Mine are already done, along with a copy of all my completed Form 1's and Form 4's, and a copy of my trust and Schedule A. They are in the NFA safe here at the house, and another complete set in the safety deposit box at the bank.
My sister is my executor, and has a copy of my will, which mentions a DVD in one of the gun safes. That DVD has video of all my NFA stuff, plus "regular" firearms, pokey stabby things, etc. This way she can visually match them and not have to guess. She also has an Excel spreadsheet that lists the firearms, (maker, model, serial number, barrel length, caliber/gauge) and who each one of them goes to. A rough estimate of resale value is listed on each, in case the recipient wishes to decline it. That way she can sell it and not be ripped off.
Since I have a trust, it's pretty easy on the NFA stuff. The contact info of the trust beneficiaries is in an envelope labeled "GUN STUFF". The combinations to the safes, along with alarm codes, are in there.
I have a relatively decent number of firearms (50+) and wanted to make it easy on her.
Was it a fair bit of work? Not really, I did it over a couple of weekends. Most cell phones will shoot video, and you can burn the clips to a DVD very easily.
I also created an "online/computer" will. It't got a list of all my electronic devices, passwords, email accounts, along with online usernames and passwords. That's written down in a small memo book, and not recorded anywhere else in any kind of electronic form. That book stays in the main gun safe in a fireproof box.
I also have a letter on who will take care of my dog. Because I'm always going to have a dog.
Hope that helps.