Can I just ask, shouldn't it be possible to run some sort of flash on the DS? I think I read somewhere it didn't have enough power, but surely it could at east run a watered down version? If my friends MP3 player can run flash it must be possible.
SUPER can convert between DPG and FLV.
You could use another program to convert the FLV first and then convert it to DPG from there.
If your's has buttons, you could just capture a video of your flash movie. Just use Fraps or a similar program. (Fraps makes an ugly watermark but if you want you can just get the paid-for version *cough*throughothermeans*cough*)