How do I play my videos in the correct aspect ratio on the Xbox?

If I go to play a video where the pixel ratio in the file doesn’t match the aspect ratio (such as from a DVDRip), it shows fine in the Plex Web Player on my Plex Server, but it spits out a squished mess on the 360.

I can correct for it with “stretch” when the correct AR matches my TV, but when the correct aspect ratio is 4/3 (Old NTSC) or 5/4 (PAL), it can’t handle it, and just spits out ugly unwatchable garbage.

Is there a way to fix this? If this is a bug (I think it might be) is there somewhere else I should be reporting it?

Thanks.