Weld Table Coating

I just finished watching the “This Tool Helps You Drill Holes In Your Welding Table” video and towards the end, the table looks like it went from having the hot rolled mill scale to a matte black look. Was the table coated with something or is it just the lighting with an oily surface that made it look black? If it was coated, what was it coated with? Thanks

Only difference is lighting between the shots and maybe a fresh layer of WD-40