Seriously, folks, I've just discovered how to display any flash fullscreen!

...at least with Firefox...

After you open a flash, select part of the title and, still holding down the mouse button, drag the cursor down over the flash to select some tertiary HTML. (Don't worry, even non-geeks can do this.) Right-click to the right of the title, and click "View Selection Source". A DOM Source of Selection window will open with some text highlighted. Scroll to the top, click on the text at the top, Use the Keystroke Ctrl+F, and copy and paste the following paragraph into the Find: box at the bottom of the screen.

embed src="http://uploads.ungrounded.net/

If it doesn't automatically select some text, click the Next button just to the right of the Find: box. Select everything between the selected " and the following ". Copy and paste the selected text into the URL box at the top of the window, then press the Enter key.

Ta-da!

I'm pretty sure there are ways with IE and most other web browsers to do this. If you find a way, feel free to comment with your answer! %u263A