Please explain how to use Speed of Tape indicator?

You specify interval in seconds In the settings and the histogram shows the amount of transactions/prints during this time.... quantity/time = speed. This indicator should be enabled on the tick- or volume chart. It is not very illustrative on the other types of chart (if there is small area with great speed on the bar, it will mark by color the entire bar...) and auto-filter (smoothing) can be disabled too... then it will be transparent. Thus it is better to use charts with a small time frame ... otherwise the speed record smeared.