Know the unsophisticated method for measuring transport speed on a vibrating conveyor, such as this model Velocan vibrating tube, which is 250 mm diam.  by 4.200 mm long.

Just a key chain, a watch with a seconds hand (or your mobile phone´s chronometer) and  the distance between the point of entry and exit are needed.

Measure the elapsed time, divide by the distance and we have the transport speed.

In this case they were 21 secs in a stretch of 4,2 m which gives a velocity of 0,20 m/s or 20 cm/s (the usual for denominating velocities in vibratory equipment, although old fashioned).

Simple!