Event video not playing when published in Captivate 8

I am using Adobe Captivate 8. I have recorded some videos in MP4 format which have been converted to f4v format using the Encoder application.

Once I insert an event video into a slide and preview it the video works well.

However on publishing it to a computer the video does not display and I am presented with a white box at the top left hand side corner of the screen which has moving waves.

Any ideas?

Thanks,

Liam