As far as is skipped through the video it is about the material editor, so i suggest u want to add a constant into ur material…
U do this normally by holding down 1 one ur keyboard and left click, BUT u can also do it by searching in the Palette(on the right side) for “Constant” and dragg it into the space. - Do that by holding left mouse button down, move ur mouse to the left grid and release it…
To convert it to a parameter - Right click on the constant and on the popup click on “Convert to Parameter”