Although you can convert any flash file to a MOV file, this will not preserve the integrity of the game. If you wish the properly play a flash game on your Nintendo DS, you must add a SWF playing program to your Nintendo DS home brew. To use DS home brew, you must use a SD card and an SD card adaptor with your Nintendo DS. Card kits are available online. As of January 2011, most of these kits cost £26 to £45.
Double-click on the Flash icon.
Click "File" and scroll to "Open Recent." Select the Flash game you wish to put on the DS Homebrew.
Click "File" and scroll to "Save As." Click on the drop-down menu and select "SWF." Press "OK."
Attach your card reader to the computer using a USB cable. Insert your SD card.
Download a SWF conversion program from the Internet (see link in Resources). These programs allow you to play SWF files on the DS home brew.
Click on the SWF conversion program. Drag and drop the program onto the icon of your SD card. Drag and drop your converted SWF file onto the icon of your SD card.
Right-click on the icon of your SD card. Scroll to "Eject." Remove the card from the card reader and insert it into your DS.
Since SWF conversion programs are created by other users, they may have bugs and problems.