I found out a way to download Flash files from websites to your computer with Firefox. So I used that knowledge to download the Stand Alone Level Designer so I can access it offline. Here's how I did it:
1. Open Firefox
2. Go to the
Stand Alone Level Designer (link can be found in LDC and Arena Topics too)
3. Right click outside the animation and select "View Page Info"
4. Select the Media tab in the window that appears.
5. The link of the swf file should appear there. Select it and press the button "Save As"
6. ????
7. Profit!
8. If when you open the file it says something about internet connection, ignore it and just click OK/Accept.
It might be useful for some to have the LD offline, that's why I decided to share this.