There is a severe drawback in Adobe Flash on OS X Lion (10.7). Flash Apps that need access to Camera or Microphone i.e. every Flash Video Chat show the “Allow to Access” Screen, but there is no way to click “Allow”. Currently this can either be worked around using keyboard navigation (tab to the ‘Allow’ button and hit space to confirm) or by manually adding the Sites in the “Camera and Microphone” tab of the Flash Player Preference Pane.
Details about this bug on the apple discussion board. And the corresponding entry on adobes bug tracker.


