Hi there,
Welcome to Adobe Community.
The feature of Video Demo that you are using was introduced in Captivate 6 and yes it creates the MP4 of the video demo. In earlier version the video demo used to be in a different way where it used to generate multiple slides and that option is still available in CP6. If you do not want an MP4 to get generated please choose the below option to create a demo:
Image may be NSFW.
Clik here to view.
Hope this helps!
Thanks!
