ASP.NET Asynchronous operations

Im new to asynch operations in ASP.NET and hopefully someone can help me clarify some questions.

Basically, I have a video encoding process that im running on a website after a file upload, but the encoding process takes some time, and during that time, on a synchronous operation, the website 'looks' like its hung. So id like to put the encoding process on a different thread all together so that i dont loose interactivity with my site. I found this website to be helpful:

http://msdn.microsoft.com/en-us/magazine/cc163725.aspx

The first example has this code:

    void Page_Load (object sender, EventArgs e)
    {
        AddOnPreRenderCompleteAsync (
            new BeginE ...