Streaming live TV on PC to watch video clips from different websites like Justin.tv and ustream.tv is really easy with the BlackBerry PlayBook. Usually, flash sites will slow down your PC if you have too many open at once, but it is possible to open about 5 streaming websites at once and the PlayBook doesn't slow down at all. Some videos may take a little while to load and the websites are not as friendly for touch devices.
You can easily go to full screen or to the small screen within the browser. Live streams from ESPN3 work pretty well on this device too. The first time loading the site can be a bit slow but after that it should be much faster. The ability to zoom in and out on this site is cool, but there is more of a lag than on other streaming websites.