Comentario oficial
Thanks for the video -- but this is perfectly normal; you have momentarily sped or slowed the platter speed above or below the set rotation speed, the platter is returning to it's normal speed.
What you're seeing when you initially drag it is the strobes moving backward as the platter speed slows, then they appear to move forward as the platter speed returns to zero -- it's not speeding-up above the zero-speed, the same as when you push the platter, it first moves the strobes forward as it's moving faster, but then the platter speed slows back to resume the zero-speed.