Some browsers have trouble with YTMND. Make sure your version of flash isn't ancient. Opera 9.22 can actually view the newer ones that have the flash loader (like this one) but older versions of Opera cannot properly. I'm unaware of any difficulty Firefox or Safari might have. All I can offer is throw open IE 6 or 7 and paste the link in to see what happens.
Or, since it's pretty easy to pull content from HTML on YTMND, have a
link straight to the GIF.