In an application with vibration (like in a car or whatever), for sure -- tinned ends are definitely not appropriate. But tinning is reasonably common for speaker cables and other similar things, though, I've found. But, I agree, still not preferred/recommended.

IPC 620 certification says you should never tin or twist a wire that you will be crimping, as it will change the current that is flowing and could ruin the crimp of the wire to the terminal. I love how you show the tool and how they should be used, but is it possible to link, display, or cite the documentation to back up your awesome demonstrations? Other than that you are doing a great job! Keep up the wonderful work.