The Unity web player has spoiled me. These dumb un-resizable windows with clutter all around them make me wish they were all Unity-fied. You? 
right click the webpage
view source
find: “probablytheflashgame.swf”
put it in your URL
full screen (sorta)
But that takes longer than right click left click.
I has idea.
Make an extension that allows you to full screen flash, with a push of two buttons (one to start, one to select flash content)!