Now when you take a screenshot from a video, there will often be black bars because of the slimmer formate of the video. But the effects in the app treats them as well, so in effect you get a screen filling image. I like the translucent dock, showing the "spotlight" so well.
When I got my first Mac in 1995, the only way to personalize the screen was to make tile
walls out of Apple's supplied tiny, tiny pictures (Really. Like 20x30 pixels.). Or one could use a shareware app called Décor. Now, two decades later, Apple has *almost* caught up to the capabilites of this app made by a single Frenchman. For example, his app could scale the image so it was not partly hidden under the menu bar. Apples OS still can't do this, nor with the dock, or on the iPad. On the iPad one can't even use an image which is smaller than the screen in either dimension, resulting in blurry photos, cut-off heads and whatnot. But hell, with 800 people working on the iPhone camera, I understand it's hard to spare a man to improve this pathetic state of affairs.
Apple makes FANTASTIC products. So why do they always insist on spoiling the experience with the occasional screaming misstep, like this, or for example mouse cables which were so short they could not even reach to the other side of a laptop!?