I didn't watch the whole video. . . Lost interest after seeing his "work" sneakers. After hearing his definition of grout, as "soupy concrete". . I just turned it off.
Only my opinion, but I would have a second thought at filling your brick column with concrete. The mortar holding the column together needs to resist the outward force of the fluid concrete. The mortar joint may reach desired compressive strength. . But the bond strength of the mortar to the brick is going to be the decision maker.
Around my location, a cubic foot of concrete weighs approx 135 pcf. An 8 foot high brick column, with a 12"x12" hollow cavity, when filled with concrete, would have approx 1000 lbs of force wanting to blow the bottom of that column out.
My thoughts are with the others. . Form and pour the column. . Then brick it.
If you absolutely must build the brick first. . Maybe fill it in several lifts to lessen the force acting outward on the brick.