Hold on LordMelkor, something might have been misunderstood
I know that the problem you're having is really strange but it shouldn't be OS related. as far as i know, both OS's use corevideo for displaying the video. An older release used "Mplayer OS X". So as far as i know, mplayer does have a render, and that option might be hidden from the newest release, and since anime_layer updated mplayer os x interface and people were reporting problems with the render itself, it must have been some reason to "delete" the option.
Well, i don't know much about mplayer compilation (i've tried so many times, and always failed) but i know there are command line options the you can put to use something.
I can give a test tomorrow and check some commands to see if something happens or better, if the problem is fixed. You could also use quartz or quicktime as the render of mplayer os x (i guess that's the option, not in my mbp at the moment) to see if it works, since you can view AVI's with quicktime.
In any case, don't think that someone doesn't give a damn. the problem could be mplayer itself too (that's usually the problem of using SVN versions of software).
I'll check tomorrow if i can, for a few commands to see if we can get more information about this, i too have a problem with mplayer os x and seems nobody has the same
