Based on Spinal's command line options for conversion here I wrote a little batch file for easy conversion. Just drag and drop your video on the batch file, select your video format and you're set. Grab it here: http://www.mediafire...stjgkp3nk39nhht or http://pastebin.com/NSKNdFwk You also need a file called FFmpeg.exe. You can get that here: 32-bit: http://ffmpeg.zerano...s/win32/static/ 64-bit: http://ffmpeg.zerano...s/win64/static/ (Just download the one at the top of the list.) If you want to download YouTube videos, you can find an easy-to-use tool here: http://www.youtubedownload.com/ Put ffmpeg.exe and 3dvideo.bat in the same folder, then drag and drop your video file onto 3dvideo.bat, or pass its filepath as the first parameter on the command line. Select your video format, desired quality and whether you want the window to close when it's done, then just wait for it to finish. It will output as filename_3d.avi or filename_2d.avi. You then take the resulting avi file and put it on your SD card in the same folder where your photos are stored. It has to be renamed in order to show up on the 3DS, however. Change the name to LLL-NNNN.AVI where L is a letter and N is a number. For example, VID-0001.AVI. Note that NNNN cannot be 0000 and you can't use a name that's already in use by another file; for example, if you already have a photo named HNI_0050.JPG, then you can't name your video file HNI_0050.AVI. Then just boot up the Nintendo 3DS Camera app, touch View Photos/Videos and search for your video. Apparently, your videos can only be 10 minutes long or they can't be viewed (I haven't tested it myself). So if you want to view a long movie or something you'll have to split it up into 10 minute long segments.