How to disable forwarding for slide videos but keep replay option enable? Is there any way for this.

I suppose you talk about the default playbar, since it is slide video?

Take out that playbar and create a custom Replay button. It is rather easy, you need this action:

Expression cpCmndGotoSlide = cpInfoCurrentSlide – 1
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More information 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