they are really cheap, and if you plug one end into the 3DS headphone jack and the other into your microphone input on your camera, you will get perfect audio from the game, and you wont have to worry about backround noise and the like.
the better quality of video and audio you use, the more popular your video's are bound to be ;P
if you are going to record cutscenes or gameplay from Dream Drop Distance, i would recommend getting a male to male 3.5 mm audio cable like this one:
http://www.amazon.com/Cables-Unlimited-AUD-1100-06-6-Feet-Stereo/dp/B000SE6IV8/ref=sr_1_1?ie=UTF8&qid=1333320121&sr=8-1
they are really cheap, and if you plug one end into the 3DS headphone jack and the other into your microphone input on your camera, you will get perfect audio from the game, and you wont have to worry about backround noise and the like.
the better quality of video and audio you use, the more popular your video's are bound to be ;P