So you need a toggle to turn it on or off? I stripped this from RadioBot to make you able to do just that. just type !youtube on or !youtube off to toggle.
Code:
on *:TEXT:!youtube*:#: {
  if ($nick isop $chan) {
    if ($2 == on) {
      if (%youtube.On. [ $+ [ $network ] ] [ $+ [ . ] ] [ $+ [ $chan ] ] == $null) {
        set %youtube.On. [ $+ [ $network ] ] [ $+ [ . ] ] [ $+ [ $chan ] ] 1
        msg $chan Youtube Info is now enabled on $chan .
      }
      else {
        msg $chan Youtube Info is already enabled on $chan .
      }
    }
    if ($2 == off) {
      if (%youtube.On. [ $+ [ $network ] ] [ $+ [ . ] ] [ $+ [ $chan ] ] != $null) {
        unset %youtube.On. [ $+ [ $network ] ] [ $+ [ . ] ] [ $+ [ $chan ] ]
        msg $chan Youtube Info now disabled on $chan  $+ . 
      }
      else {
        msg $chan Youtube Info was already disabled on $chan  $+ .
      }
    }
  }
}


and then add this to the 'on text' events to make them check if they should fire (make sure to close the bracket on the end of the event, ofcourse)
Code:
if (%youtube.On. [ $+ [ $network ] ] [ $+ [ . ] ] [ $+ [ $chan ] ] != $null) {


Have not tested it in this particular script but it should work, i use it all the time.