if some one wants to change the  thumb pic if you  don't  want to take a thumb  in the  beginning  of the  video

you  can change it from here

Line 259

/flash/modules/video/inc/functions.inc.php

function grabImages($sInputFile, $sOutputFile, $iSecond = 0, $bForse = false)

I changed it to

function grabImages($sInputFile, $sOutputFile, $iSecond = 5, $bForse = false)

This now tells it to make a thumb 5 seconds into the video.