It has already been proven that these machines don't work on german television: http://www.youtube.com/watch?v=M6iBzlXar50 Still german airport security is using x-ray machines now, at least in Hamburg.

If you compare the actual frames, you'd see that the 4k variant has insane blocking, which destroys all the information. 1080p just blurs these sections, but still looks way better because it doesn't create 8x8 blocks. Youtube can only encode to 4k because they use an inferior entropy coding and no proper deblocking. Otherwise 4k wouldn't run on any but the fastest CPUs, even without the flash overhead. As it is, the 4k variant is inferior to 1080p and 720p because of the massive blocking, I don't see why Youtube wastes space and bandwidth on this unless they are just experimenting.

It was just for testing purposes, it's much easier to see artifacts at that low bitrates.

People still use Xvid, which is nearly 8 years old.

This is completely wrong, Theora is *escpecially* bad at low bitrates, I recently made a small comparison of Theora/Thusnelda and H264/x264 encoded 1080p videos, both looked very watchable at 4Mbit, but at 2Mbit problems for Theora/Thusnelda started, and at 1Mbit it was just plain awful. 2Mbit Theora/Thusnelda couldn't nearly reach H264/x264 quality at 1Mbit.

that's right, now combine that with proper mastering (http://en.wikipedia.org/wiki/Loudness_War) of vinyl compared to CD (for jazz, pop and rock at least).

This makes no sense. A properly encoded and decoded file should be sample accurate, so there will be no shifts in samples.