Just go into the Webcontrol page by entering your box's IP address into your web browser. Click the "Television" Menu then click on Bouquets. Within each bouquet each channel should have 2 little TV screen icons on the right. Click the second one to start streaming.
On my google Chrome the streaming did not start automatically so I just clicked on the m3u file that it downloaded and told it to always open. On the odd occaision I have had to click "play" again on vlc because the streaming stopped but in general it was pretty solid
And yes you can stream from the second tuner while the first is tuned to something else on the TV