So Facebook has been keeping videos that you deleted , even videos that you've created, never published & deleted. Facebook refuses to reveal if the videos were viewed by any of their employees or used in any way.
1) The company today blamed a bug for the error and promised to delete the clips
2) It also confirmed the deleted content was never publicly shared, although it remains unclear whether Facebook used the footage in any other way
Facebook blames a 'bug' for keeping copies of users' deleted videos | Daily Mail Online