Try this:
VideoLengthInSeconds = 60
RunVideoEveryXMinutes = 30
TheVideoFile = C:\MyVideoFile.wmv
Loop
{
Run, wmplayer.exe "%TheVideoFile%" ;run the video in wmp
Sleep, 3000 ;wait 3 seconds
SendInput, {F11} ;send F11 to make it fullscreen
Sleep, % VideoLengthInSeconds*1000 ;wait while video is playing
Send, {alt down}{F4}{alt up} ;close the wmp
Sleep, % RunVideoEveryXMinutes*60*1000 ;wait after the video was played
}
;Use Esc to exit the script
Esc::
ExitApp