Bug: Meta Boxes Removed from Posts

Your code on lines 279-288 in l7-admin-help-videos.php is removing meta boxes from the Post post type, not the l7_help_video post type. The code you have is:

public function remove_ex_box(){
	remove_meta_box( 'authordiv','post','normal' ); // Author Metabox
	remove_meta_box( 'commentstatusdiv','post','normal' ); // Comments Status Metabox
	remove_meta_box( 'commentsdiv','post','normal' ); // Comments Metabox
	remove_meta_box( 'postcustom','post','normal' ); // Custom Fields Metabox
	remove_meta_box( 'postexcerpt','post','normal' ); // Excerpt Metabox
	remove_meta_box( 'revisionsdiv','post','normal' ); // Revisions Metabox
	remove_meta_box( 'slugdiv','post','normal' ); // Slug Metabox
	remove_meta_box( 'trackbacksdiv','post','normal' ); // Trackback Metabox
}

Please replace that code with:

public function remove_ex_box(){
	remove_meta_box( 'authordiv','l7_help_video','normal' ); // Author Metabox
	remove_meta_box( 'commentstatusdiv','l7_help_video','normal' ); // Comments Status Metabox
	remove_meta_box( 'commentsdiv','l7_help_video','normal' ); // Comments Metabox
	remove_meta_box( 'postcustom','l7_help_video','normal' ); // Custom Fields Metabox
	remove_meta_box( 'postexcerpt','l7_help_video','normal' ); // Excerpt Metabox
	remove_meta_box( 'revisionsdiv','l7_help_video','normal' ); // Revisions Metabox
	remove_meta_box( 'slugdiv','l7_help_video','normal' ); // Slug Metabox
	remove_meta_box( 'trackbacksdiv','l7_help_video','normal' ); // Trackback Metabox
}

https://wordpress.org/plugins/l7-admin-help-videos/