Facebook "show all"

The possibility to show / promote single clips in my Facebook profile works very bad.
There's allways a wrong image for the video. Sometimes that's so stupid because it's absolutely not belonging to the theme of the clip.
For example: When i'll link a video with a eagles portrait close up, ... how can there in Facebook appear the face of a little child, even if while linking there seems to be the right image at the first place ???
:(

I just did a trial and it worked fine - however, here is how I did it:

1. Seek out the clip on P5 and open it's page.
2. Copy the URL from the address bar in full.
3. Paste the URL into your FB message, text whatever. ...
it then should do a search and create a pseudo page with thumbnails.... it will give you several choices of thumbnails to use, so scroll through them until you find the one from the specific clip.

Voila! :)