Video Demo isn't playing back after publishing (Captivate 8)

Hi. I have a Captivate project where one slide is a video demo. Unfortunately, after I publish the file and view it, the video demo slide doesn't show the action - it only shows the loading icon. Before trying the video demo solution in Captivate, I had used SnagIt, which saved it as an MP4. After bringing in the MP4 and publishing, the slide is blank when playing back. The only thing that has worked was publishing to a pdf. The pdf version plays back perfectly. The problem is, we can't publish a pdf for our LMS. Help! Thanks

Deanna