I too have watched one or two of these videos and I can't help but wonder how financially destructive this gig would be if the damage was real at the level and type of equipment being restored. That is probably why there are so many fabricated restorations, including the offending light oxide dust on top of closed equipment.
Well yes, and no. Of course the dirt is fake as in it has been manually applied but the damage (caused by the idiot) is very much real! As has been discussed in the previous thread, all the "after" shots and clips of the units operating are actually the before shots of the unit prior to being destroyed by a monkey. That cheap tape deck, and now that cheap amp, will never run again. There is no consequence to them because the got it for probably $5-15 at a yard sale, flea market, Ebay, exc. The real cost is the damn ewaste from destroying working gear. Assholes! 
Perhaps I should have been clearer; I was referring to the videos where the person says it finds a piece of equipment "in the woods" while it only has a layer of fine dust and a drip of mud here and there.
The reverse videos are pretty much as you describe, but they are only viable due to technological obsolescence and the change in habits of the general public. These equipments would be ewaste anyways, especially on the more developed world where these were/are more plentiful and cheap(er).
Over the years I was given several AV receivers in pristine condition when they cost US$300~1000 new in their day. I did restoration on some just to satisfy my curiosity, but the resale value is close to zero. If I were in my birth country, I could have sold these for quite a lot more given they are much less common as they were luxury items.
Of course, there are other items where the market simply vanished or was reduced to severely low levels - case of the tape deck or a VCR, for example. In this case it is much more understandable that someone would make such video to get more return than its resale value. Not that I like it or would do it, but it is a hustle like any other.