jwplayer playlist is not working in mobile

问题:

hi all,

              jwplayer("XXX").setup({
               playlist: [
                 {file: "http://www.youtube.com/watch?v='.$youtube_id1.'"},
                  {file: "http://www.youtube.com/watch?v='.$youtube_id2.'"}
                  ],
                width: "560",
                primary: "flash", 
                height: "315",
                image: "/hqdefault.jpg", 
                autostart: "true",
                skin: "/vapor.xml"
              });

i have a problem, i cannot play this playlist as a whole in mobile, only playing the 1st video then stop. in desktop version is working well.

i use jwplayer 6 premium

anyone can help me? im stuck here:( thank

Note: if i changed them to local files(videos), it works...