Adding new override for COM_COMMUNITY_ACTIVITY_VIDEO_LINK_TITLE without changing anything, brakes video link in video post header. Erasing just dot at the end of constant value (added a <a href="_QQQ_%1$s_QQQ_">video</a>.) breaks link totally.
Also, styling for video header is located in librarries/videos.php which is strange solution since photos are handled from theme.

on your override string please change value

"_QQQ_%1$s_QQQ_"

_QQQ_%1$s_QQQ_

Strange, could not remove " from Joomla back end. Editing override directly in:
...\language\overrides\en-GB.override.ini
does fix this issue.

glad to know that..