How I can use Kivy (Python) camera
<p>I try to use uix.camera widget and show some wideo from my web-camera.
I looked into the documentation and try to use this simply code. But it's just show me a white creen withoud any video (I enabled playing). 
What I'm doing wrong? 
Maybe some useful docs\tutorial exist (because from official documentation I understanding a little from many). Thanks for any help.</p>

<pre><code>import kivy
kivy.require('1.9.1')

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.camera import Camera

class MainApp(App):
    def build(self):
        return Camera(play=True)

if __name__== "__main__":
    MainApp().run()
</code></pre>