I want to display in the facebook popup the same text as the one display in the article.

My solution :
1 - creation of the hidden field 'social description' with the following prefix:{{video##0##description}}{{item->text}},
2- I have enabled the social website support as description for 'social description' field
3 - in the core item 'Description' I have desabled the social website support,
4 - in the template renderonly zone, I have placed the 'social description field'.