mp4 file format for video and mp3 for audio. To allow other file formats, add the following code in your theme or plugin. function rt_custom_allowed_types( $types ){ if ( isset( $types[0] ) && isset( $types[0]['extensions'] ) ) { if ( is_rtmedia_upload_video_enabled() ) $types[0]['extensions'] .= ',mov,mpg,flv,wmv,mkv,webm,ogv,mxf,asf,vob,mts,qt,mpeg,x-msvideo'; //Allow video types of file to be uploded if ( is_rtmedia_upload_music_enabled() ) $types[0]['extensions'] .= ',wma,ogg,wav,m4a'; //Allow audio types of file to be uploded } return $types; } // filter plupload allowed file formats add_filter('rtmedia_plupload_files_filter', 'rt_custom_allowed_types', 10, 1); function rt_custom_allowed_types_admin_settings( $types ){ $allowed_video_string = implode(",", $types['video']['extn']); $allowed_audio_string = implode(",", $types['music']['extn']); $allowed_video = explode(",",$allowed_video_string.',mov,mpg,flv,wmv,mkv,webm,ogv,mxf,asf,vob,mts,qt,mpeg,x-msvideo'); $allowed_audio = explode(",",$allowed_audio_string.',wma,ogg,wav,m4a'); $types['video']['extn'] = array_unique( $allowed_video ); $types['music']['extn'] = array_unique( $allowed_audio ); return $types; } // filter to show allowed media types in admin settings add_filter('rtmedia_allowed_types', 'rt_custom_allowed_types_admin_settings', 10, 1);rtMedia uses mediaelement.js to play video and audio which might not support the types you have allowed using the above filters. In this case, you will need a custom media player that you can use with rtMedia to play audio/video files.