How to blank preview screen on embedded video

Creating an Impress presentation with embedded video on some slides.

One of the videos contains a surprise. Unfortunately, when I embed it, the resulting slide shows the surprise image as a preview still that lingers on the screen for a moment before the video kicks in. That, of course, kind of blows the whole idea of a surprise.

Is there any way to change that – I imagine it’s a preview image in the video file – to a blank, black screen?

I’ve tried rendering as mpg, mp4, avi and webm formats from Kdenlive, and all have the same issue.

Ideas most appreciated!

Thanks.

System info: LibreOffice 4.2 Impress, Kdenlive 0.9.6, Ubuntu 14.04