time stamp in chat recording

[wlynn]

The recording of the meeting chat has a time stamp for each line. This time does not appear to correspond to the video recording time stamp. Any thoughts on why?
More detail: It is my practice that when a new person joins the meeting, I welcome them in the chat so that everyone know they have joined and I can note in the meeting minutes that they joined the meeting at a specific time. These times (e.g. 00:17:24) do not correspond to the time noted in the video recording. For example at the 8 minute mark, I show a participant joining the meeting in the video recording, but in the chat they don't seem to have joined until 00:20:15.