koreus.lua: small fix-up

(cherry picked from commit 4491de9a6b93ac1838eaa0ef89ad97eddbcf4960)
Signed-off-by: Pierre Ynard <linkfanel@yahoo.fr>

share/lua/playlist/koreus.lua

@@ -47,9 +47,10 @@ function parse()
 			_,_,arturl = string.find( line, "href=\"(.-)\"" )
 		end
 
-        vid_url = string.match( line, '(http://embed.koreus.com/%d+/%d+/[%w-]*%.mp4)' )
+        vid_url = string.match( line, '(http://embed%.koreus%.com/%d+/%d+/[%w-]*%.mp4)' )
 		if vid_url then
 			return { { path = vid_url; name = name; description = description; artist = artist; arturl = arturl } }
 		end
 	end
+    return {}
 end