I can't be sure but think the wood is oak
At 1:45 he's mixing either a powdered dye or finely crushed shellac flakes.
- Dye is different than stain - stain is pigment or pigment & stain. Dye has no pigment and when dry is translucent. In response to your question dyes can mixed into water, an oil base solvent such as lacquer thinner or with lacquer thinner with some lacquer in it.
- Shellac flakes come in a variety of types/shades and are mixed into denatured alcohol. When applying any shellac, you cover an area and don't go back over it.
I'm guessing he's using dye
His 2nd step appears to be a tinted grain or pore filler...a common practice for woods such as oak. When the filler dries you sand to get it off the surface wood, leaving it the colored filler in the pores only.
- At 5:16 I don't know what he's doing. He mentions that its diluted, but it's a water clear liquid and he's applying it with a rag, so I'm not sure of what he's using. Especially since in the next step he's sanding the surface with a 220 grit paper. Since he's sanding my guess is that he was applying some film finish. While it could be lacquer, that would be highly unlikely. It could be a waterbased type of varnish/poly
At 12:45 He's padding on the finish - this is only done with varnish or shellac. It probably is shellac (a dark shellac such as buttonlac) or shellac made to work as a toner (has dye mixed with the shellac). This adds some color, and when dry adds a layer of finish. NOTE: That he's applying these last coats with what's known as a 'bumper' or 'charger'. That's a piece cotton wrapped into a ball and placed inside of a piece of flannel
Bob "Boardman" Borders