I have a number of ripped videos on my Mac Mini attached to my network. The ATV2 can get to the share, and it can see the files there. On the ATV2 display, some video folders come up with a blue dot to the left of the title - and these seem to play okay. But the other videos come up with a folder icon, and when I press enter on the remote control I get an error message saying that there was no content. I am able to play all of these videos on my MacBook using VLC. Is there a reason why some of my video content is being recognized and others are not?