Lord Grievous said:
No they're not, the Bespin escape clip for instance is a 720p TS stream with no black bars and it plays perfectly on my widescreen monitor. I've noticed that some of the Facebook clips are stretched, but I think that's because of some other reason. If you play a 720p or 1080p clip with no black bars on a widescreen monitor it will create the bars itself.
Yes, but not in AVCHD or Blu-Ray format, these formats have a resolution standart of 1280x720 (16x9) for 720p and any other aspect ratio has to have black bars to fill the picture to the same resolution. An AVCHD with a resolution of eg. 1280x544 just won't work.
But if the bars are already part of the image it will still create them and thus you have two sets of black bars surrounding your image, which makes the image look even smaller.
And this is absolutely false; because the black bars that are already in the picture conform the picture to a 16x9 AR, the player will not add any bars because it will be playing a 16x9 video. The only issue is the black bars taking up data space but it isn't much because they stay the same all the time so they're easy to compress.