Yeah, the ShooTag thing is totally bogus.

Viewing magnetic recordings with magnetic particles used to be a standard maintenance tool. It was used to check tape drive head alignment. There was a liquid with iron particles in suspension into which you could dip a strip of tape. When the solvent evaporated, you could see the data tracks. A non-destructive version was a hand-held viewer, with a window on top and a thin plate on the bottom, filled with a fluid containing iron particles. You could press this against a tape and view it.

These were sometimes used in data centers during the transition from 7 to 9 track tape drives, when an incoming tape had an unknown format.