Hi Wong, nice to see you back 
The way shown in the video is the way to do it. Hold the tap in the 3 jaw chuck, and just allow the work piece to revolve on a spindle.
Something like a square bar held in the tool post with a spindle sticking up.
The square bar can have a taped hole to hold the spindle which is screwed into the taped hole.
I'll say what I did. 16x20 flat bar drilled and taped 6mm. The screw was 6mm (Hex head)so a 10mm bar (to act as the spindle) was taped 6mm was screwed on, then turned down to 8mm dia. The hole in the worm was 8mm.
The spindle part can be turned to the correct length so that when tightened it allows the pulley to freely rotate. (With a bit of oil)
Hope you can understand that.
DaveH
The way shown in the video is the way to do it. Hold the tap in the 3 jaw chuck, and just allow the work piece to revolve on a spindle.
Something like a square bar held in the tool post with a spindle sticking up.
The square bar can have a taped hole to hold the spindle which is screwed into the taped hole.
I'll say what I did. 16x20 flat bar drilled and taped 6mm. The screw was 6mm (Hex head)so a 10mm bar (to act as the spindle) was taped 6mm was screwed on, then turned down to 8mm dia. The hole in the worm was 8mm.
The spindle part can be turned to the correct length so that when tightened it allows the pulley to freely rotate. (With a bit of oil)
Hope you can understand that.
DaveH