The code below binds the text property of a textinput component called "myStatusArea" to the text property of another textinput component called, "myStatusAreaHTML" every time the "draw" event is called. I chose the draw event in this circumstance because it occurs on almost every change a text box goes through.

// this binds our status area to a second status area that
// has html enabled so we can see html output
import mx.data.binding.*

var from:Object = {component: myStatusArea, property: "text", event:"draw"};
var to:Object = {component: myStatusAreaHTML, property: "text"};

var myBinding:Binding = new Binding(from,to);

Now whenever the textinput, myStatusArea, changes the text value is copied to the second textinput text property.