How can I stop slide video

You didn't get an answer yet, which is rare. Mostly it means that your question is not detailed enough, it is even confusing for me. I will try to summarize what I understand so far, and add some clarifying questions:

• You are talking about slides in a cptx project on which you inserted a video with the status 'slide video'. That means your video is synchronized with Captivate's Timeline, contrary to video inserted as event video.
• Using the term 'stop', do you mean pause the video with a dedicated button, and eventually continue with the Play button later on? Are you pointing to the Pause/Play button in one of the default playbars?
• Since you talk about slide video, I presume you are working on a non-responsive project? Can you confirm?
• 'Replay': do you mean to replay the slide which would mean to restart the video from its first frame? The default playbars do not have a Replay slide button,, only a Rewind button which will restart the complete project. You can create a custom Replay slide button which would be valid also for a slide video. You'll need this advanced action for that button:
     Expression cpCmndGotoSlide = cpInfoCurrentSlide - 1
  
  More informations about Replay can be found in this blog post:
     http://blog.lilybiri.com/replay-or-reset-slide
  or if you prefer a Captivate tutorial: http://blog.lilybiri.com/replay-slash-reset-slide-2-captivate-tutorial
• Since you also applied the tag 'Audio', want to know if the audio is embedded in the video or did you create the audio within Captivate to synchronize with the video?
• It is mostly useful to mention the exact version number you are using, as found under Help, About Captivate. Please also the OS you are using.