Help?
Since you said flash game, I'm assuming you have a locally recorded video. You'll need to put it online somewhere else (Youtube is good for this) and provide the video link for your run submission.
Be warned, Flash Games are subject to harsh standards to be added to the site. This is due to the high volume of short runs for obscure flash games that are a dime a dozen. Flash games have to be very notable or provide a very convincing run to be added. Your game may not get added for that reason.