Post event video on facebook

Hi,
if someone create an event and post a video into. Go into event and click on the video. Sharing this link on facebook you will get a fine content but clicking on it message "Download File" appears instead of playing the video.

Regards

Edit:
Problem only exist if meta property="og:image" is set in index.php

Is it possible to set the og:image in event video section same as in video section (there my og:image set in index.php gets overwritten)?