Lags and/or my gamepad controls are reversed.
Google Chrome.
Chrome probably uses its own version of Flash Player.
Type this into the url bar: chrome://plugins/
Search "Adobe Flash Player", you should see two "Shockwave Flash".
Disable the plugin which is located in "\Google\chrome" and restart the browser.

The game does not start, the frame remains black.
Internet Explorer.
Your Flash Player version is probably older than 13.
Check your version: http://www.adobe.com/fr/software/flash/about/
Update your Flash Player: http://get.adobe.com/fr/flashplayer/
Be careful to the "McAfee Security offer" checkbox on this last link.