The key parameter that enable the use of video recording to calculate the vehicle speed is the reliable frame timing. In cases of doubt it would be useful to examine the recording/playback system by a lightboard (a frame interval timer), because the examination of the file itself does not provide certainty as to the embedded system-time, the playback/recording time rate, the pattern of skipping frames, exposure time, etc. This paper briefly reminds the essence of using the lightboard and deals with: (1) method for identification of the elementary time interval ensuring stabilization of time parameters (crucial for vehicle speed calculation); (2) verification of recording frequency of a popular amateur high-speed camera declared by the manufacturer; (3) deriving formulae to calculate the uncertainty range of photo exposure time based on the configuration of the illuminated LEDs (Light-Emitting Diodes). Calculations are illustrated by the adequate examples.