2 mins preview

Hi,

I've been trying to implement "2 mins preview" functionality for live stream and I tried using "SetPreviewMode(true)" function of "roVideoScreen" but it's not working. Following is the piece of code:

port = CreateObject("roMessagePort")
screen = CreateObject("roVideoScreen")
screen.SetMessagePort(port)
screen.SetPreviewMode(true)
screen.SetContent(episode)
screen.Show()

Can someone please explain what is the correct way of using it?

Thanks.