This Property - MACROMEDIA FLASH 8-FLASH LITE 2.X ACTIONSCRIPT LANGUAGE Reference

Example
The following example streams an MP3 file and buffers the sound before it plays for the user.
Two text fields are created at runtime to hold a timer and debugging information. The
property is set to buffer the MP3 for 10 seconds. A new Sound object
_soundbuftime
instance is created for the MP3.
// create text fields to hold debug information.
this.createTextField("counter_txt", this.getNextHighestDepth(), 0, 0, 100,
22);
this.createTextField("debug_txt", this.getNextHighestDepth(), 0, 20, 100,
22);
// set the sound buffer to 10 seconds.
_soundbuftime = 10;
// create the new sound object instance.
var bg_sound:Sound = new Sound();
// load the MP3 sound file and set streaming to true.
bg_sound.loadSound("yourSound.mp3", true);
// function is triggered when the song finishes loading.
bg_sound.onLoad = function() {
debug_txt.text = "sound loaded";
};
debug_txt.text = "sound init";
function updateCounter() {
counter_txt.text++;
}
counter_txt.text = 0;
setInterval(updateCounter, 1000);

this property

this
References an object or movie clip instance. When a script executes,
movie clip instance that contains the script. When a field is called,
to the object that contains the called field.
Inside an event handler attached to a button,
on()
the button. Inside an
the Timeline of the movie clip itself.
110 ActionScript language elements
event handler attached to a movie clip,
onClipEvent()
this
this
refers to the Timeline that contains
this
references the
contains a reference
refers to
this