Chuck,
I didn't produce that video, but pulled it off the net when I bought a Harbor Freight tool grinder. When run, it rattled like an old washing machine. I put rubber pads underneath it and used "c" clamps to hold it to the bench. Still rattled so much that I was pretty sure I would never be able to true the wheels. The flanges had something like .03" of runout.
I followed the video instructions, mounted the spindle with mounting flanges attached on my lathe and trued them.
I can balance a nickel on the the top of the running grinder. (However, like most rotary machines, it does run through a resonant point of vibration until it reaches final speed).
You absolutely must true the wheels. I don't use carbide tools so I replaced the green wheels with type 50 white wheels and trued them with an industrial diamond.
It was fun, simple project on my lathe that led to a useful result.
Dick