Has anybody ever uploaded to their smugmug an HD video only to have it play back squished horizontally so it looks like a 4:3 aspect ratio instead of a 16:9? When I play the video on my desktop it looks fine.
Sites like Youtube, Vimeo or Smugmug prefer to have videos with specifically required settings otherwise the system changes the aspect ratio - this happens frequently.
Take a look here, they explain how you should convert your video.