This Spitfire would qualify as an amateur built experimental. Based on a design by Marcel Jurca from France. I believe this is this is the aircraft in the original youtube clip.
MJ-100 #Deford - N1940K
The prototype spitfire was all wood and subsequent versions were all aluminium. Apart from the external appearance the Jurca full scale replica would have little in common with the original spitfire which had quite a complicated structure to fabricate. Plans are $1500 if your keen to build your own!