Calculating Time Spent Using Khan

Hello.  I received the email below (in italics) from a parent this morning.  It seems that although the student is working within the Khan platform, there seems to be a significant discrepancy between their actual time spent and the time being reported.  I realize that Khan only reports student engagement but if the student is actively watching videos and working through exercises, I would think/hope that the time is reported more accurately than this.  My question, Does Khan report the entire time a video plays or is there a maximum amount of time that will be counted?  I realize that students working on exercises may take more time and thus appear as if they are not engaged so I would understand a max cap there.  As some videos are longer than others, a max could conceivably have an impact on the amount of time being reported.

Hi there. I just wanted to check in regarding ----. He is telling me he is doing the amount of time he should and we have had him use a timer. However, the Khan Academy time does not match the timers we have set. On one day I made him sit near me after he set the timer. After 30 minutes of him working, the Khan Academy said it was only 13 minutes. (I honestly questioned if he was doing it correctly until I made him sit near me and watched him set a timer.)