You aware that you'd break the copyright of the creator of the swf file?
You can't just 'steal' others work and it's
never a good idea to use such copyrighted content "just" for the developing phase etc. because at the end you might not take them out and if the owner finds out, he could potentially sue you.
So you should either ask the creator of that game, if you could use the graphics (and he might even give them to you) or you should go and make use of free content. There are hundreds of websites with such content, one popular one with also quite a few public domain releases is
OpenGameArt.org.
Besides that, have you even googled for your problem? I bet one can find an answer within a few minutes.