Then you may try to add "mp3" to the 'bx_timeline_videos' and 'bx_timeline_videos_processed ' records in `sys_objects_storage` table via the phpMyAdmin tool. Just execute the following queries:

DELETE FROM THE `sys_objects_storage` WHERE `object` IN ('bx_timeline_videos,''bx_timeline_videos_processed);

INSERT INTO `sys_objects_storage` (`object`, `engine`, `params`, `token_life`, `cache_control`, `levels`, `table_files`, `ext_mode`, `ext_allow`, `ext_deny`, `quota_size`, `current_size`, `quota_number`, `current_number`, `max_file_size`, `ts`) VALUES

('bx_timeline_videos', @sStorageEngine, '', 360, 2592000, 3, 'bx_timeline_videos', 'allow-deny', 'avi,flv,mpg,mpeg,wmv,mp4,m4v,mov,divx,xvid,3gp,webm,jpg,mp3', '', 0, 0, 0, 0, 0, 0),

('bx_timeline_videos_processed', @sStorageEngine, '', 360, 2592000, 3, 'bx_timeline_videos_processed', 'allow-deny', 'avi,flv,mpg,mpeg,wmv,mp4,m4v,mov,divx,xvid,3gp,webm,jpg,mp3', '', 0, 0, 0, 0, 0, 0);

But note, that this is just an attempt.