When can we play mp4 VIDEOS on the 3DS?

Hey everyone I just bought a 3DS on sale during Thanksgiving/Black Friday and am loving Sonic Generations and Netflix. Though I'm curious as to how to play mp4 videos . I heard that people can play the audio from the mp4 file but the video remains black. There was also talk about the new update allowing video playback, but that's only for 3D videos right?

Maybe there is a special format we can convert regular videos to 3D (but still be in 2d just a different file format) ?

I've been searching on Google but no one seems to have a clear answer. I'd really love to watch mp4 videos on this thing, the top screen it beautiful!