Facebook comments "[social:facebook_comments]" tag is available since version 3.8.8
To add Facebook comments to Youtube Gallery Theme use "Custom Layout" box.
Add the following code after [videoplayer] tag:
Syntax:
[social:facebook_comments,Number of Posts,Width,Color Theme (light by default)]
Example: [social:facebook_comments,3,400,light]
Full example:
How to make it responsive?
Add the following code to "Head Script" box (Advanced section)