Now that you posted that Rec (I have also not watched it) I see I was remiss in my post above, since I only really gave advice on getting manufactured mats.

For raw mats I do the old school 'shoot rocks with my SRV' type prospecting, although there are better ways to do it now (geological sites)

For encoded I scan every ship I can, no matter what I am doing. And every now and again I do some wake scanning outside busy stations. I built a rocket sled so this is fun. No wake is going to get away from this thing. 835 boost


iEagle Wake Scanner (Zoom zoom)

And because money is not important to me any more, I almost always take G5 mat rewards from the missions I fly, if available. Five Modified Embedded Firmware for example will go a long way at the mat trader.