youtube.lua: update to new website changes

(cherry picked from commit 0137d3be215be27d29224bd04f921e41e9cac145)
Signed-off-by: Pierre Ynard <linkfanel@yahoo.fr>

share/lua/playlist/youtube.lua

@@ -95,8 +95,8 @@ function parse()
                 _,_,artist = string.find( line, "href=\"/user/([^\"]*)\"" )
             end
             -- JSON parameters, also formerly known as "swfConfig",
-            -- "SWF_ARGS", "swfArgs" ...
-            if string.match( line, "PLAYER_CONFIG" ) then
+            -- "SWF_ARGS", "swfArgs", "PLAYER_CONFIG" ...
+            if string.match( line, "playerConfig" ) then
                 if not fmt then
                     prefres = get_prefres()
                     if prefres >= 0 then