Interacting with actionscript 3.0 using javascript

The example you posted uses the ExternalInterface class to communicate from Flash to Javascript. You can add callbacks using the ExternalInterface but if you need to trigger a function from the DOM (HTML) that goes to FLASH.

OK, now to get values from Javascript to Flash there are a few options.
You can set up a callback function using the ExternalInterface Class. Here is an example from Live Docs link text

If you need to call the Flash from Javascript without ANY Flash interaction (like to play a video or something), again you will use the ExternalInterface. Here is an AS3 example link text

Here is an AS2 example to answer your question:

//AS2
import flash.external.*;
function helloWorld():Void
{
    //Do something
}
ExternalInterface.addCallback("myFunction", helloWorld);

// HTML
<script language="JavaScript">

    flashObject.myFunction();
</ script>
...
<object id="flashObject"...>
    ...
    <embed name="flashObject".../>
</object>