Some filter have a little bit of metal or whatever from the threading process. I'm in a habit of taking a clean towel and wiping it off by unscrewing the filter around my towel wrapped finger. It takes about a second and is second nature. I've found it on nearly every spin on filter regardless of type, media, or process. It is equivalent to wiping the oil cap seal clean, or the dipstick seal. Is it doing anything meaningful? Probably not, but it makes me feel good. I would feel embarrassed to make a video and tell people to not pre-fill filters based on that though.