Instant Webcam can stream fullscreen video to multiple devices in the same Wifi Network.
All you need is a modern browser and you're good to go.
No need to set up. Just start the App and point the browser on your viewing device to the provided URL.
You can even record video straight from the browser.
Because setup is Instant, you'll find yourself using the App even if you just need to keep an eye on the stove for two minutes, check the front porch when you wait for the mail man, or watch the kids.