Add "condition: Compare playback time" to compare current playback time. And expression:VideoState to dump state of current video, for debug.
Repeat: If PlayBackTime >= 7 then Set playback time to 3 , i.e go back previous playback time
It works by my test. (Sampe capx
But skip: If PlayBackTime >= 7 then Set playback time to 3 will cause youtube player to "buffering" state. I have no idea how to solve it.