Since when the ps3 reads mp4 videos?

Hi there, I have a simple question that I hope someone can answer.

I have some videos in avi and mp4 and I mixed them in a dvd for watch them in the ps3. When I put the dvd on the ps3 and clicked on the video part; it only read the avi ones, the mp4 ones weren't recognized by the ps3. Well, I had a hard time but decided to watch the avi there and mp4 on my pc.

Now comes the interesting part, today I put the dvd on my ps3 and when I put the video icon on the XMLB I saw more videos, because at that time I wasn't fully awake I didn't mind and I put my avi video but now that I'm fully aware of everything I noticed that the ps3 recognized the mp4 ones so anyone knows since when the ps3 recognizes those files?

PS3 originally rezognizes MP4 video files, then later on they added the DIVX to it so thats how PS3 can recognize the AVI files. Back then at first PS3 cannot read AVI files. There might be some problem with the DVD.