Get a dstwo and then watch in .avi format. Converting videos to dpg takes freakin' forever.
I actually second this. After spending over 24 hours converting my video files to .DPG and transferring them on to the SD card, I can tell you right away that .DPG formatting isn't worth the headache, especially now that it's getting harder to find specific homebrew apps to read them due to many of the homebrew sites no longer being hosted or cached.
I have used many different conversion methods and most of them seem to corrupt the audio when converting to .dpg from a MPEG-2, flv or mp4 video file. It has something to do with audio decompression and additional compression when the .DPG file is being made. Perhaps if you are using a program that can create a .dpg file using a separate audio and video file (such as from a ripped DVD). After spending a decent amount of time dabbling with homebrew apps on my DSTwo+ card and converted video files I have found converting to .AVI is a far more effective. This is for two reasons:
The first is the fact that .DPG files, while formatted to the DS' hardware specs always seem to have problems when converting larger files. Even if you do get a .DPG with properly compressed audio, I have seen longer videos lose sync with the audio as the media continues to play. After going through the trouble of converting or re-rendering, it's not what you are looking for nor worth your time. And yes, being a proprietary format for NDS, the media conversion takes longer than converting to, say, a .AVI file. Both of which are container formats, btw
@Foxi4
The Second reason I recommend using .AVI on your card is because it can be rendered/ converted to 240x180 (roughly the DS' resolution) taking up a smaller amount of space and will be compatible with your other devices. Basically, it's a more flexible video format, conversion and rendering takes less time, the media files are relatively small and they play just fine on the DS with the proper homebrew app.
If .DPG files work for your card, software and files USE IT! The .DPG files are smaller and take up less space on an SD card, giving you more room for games and homebrew.
Sorry if this post is a bit long in the tooth but I have spent too much time trying to optimize my videos and I wanted to share my findings