"And another thing: There is an easter egg in the ESB disc (In the bonus features screen, go to "main menu" button and then press right). That easter egg provides nothing extra to the spactator, it just mocks him (you'll understand when you see it). So I'm thinking.... Why would someone who made a disc only for himself, as the creator of this set claims he did, put an easter egg like this in his creation?"

1) The creators obviously gave copies to some friends.
2) No one in their right mind would expect this version to never get out.
3) Why not?

"I understand that solid black is easy to compress, but how can there be more actual picture information on anamorphic format as opposed to letterboxed format? Is it simply that the resolution is that much finer on anamorphic?"

Set your DVD player to 4x3 mode, and play an anamorphic DVD. The picture will be stretched vertically, almost - if not completely - to the top and bottom of the screen. (Again, depending on the ratio of the film.) Everyone will look tall and thin.

If you play a non-anamorphic DVD, it will take up the same space regardless of 4x3 or 16x9 mode, because there's nothing to alter.

Without getting too technical....When the DVD player is set to 4x3 mode with an anamorphic DVD, lines of video are removed, so that the picture is small enough to fit in a 4x3 screen. If the DVD player is set to 16x9 with an anamorphic DVD, the picture is stretched horizontally, and now all those "tall & skinny" people are the correct width for their height.

This site has many excellent examples...

http://www.widescreen.org/dvd_anamorphic.shtml

http://www.widescreen.org/images/st4_43_nonanam.jpg

If we looked at this as a letterbox transfer, then we would see that a lot of the 720x480 frame is taken up by black space. Now, if we looked at this as an anamorphic transfer...

http://www.widescreen.org/images/st4_43_anam.jpg

Notice how less space is taken up by the black edges! The more variety of video information you have in the frame (different colors, high action), the less you are able to compress the video. Still scenes take up very little space, whereas scenes with movement are harder to compress. Explosions and such do not compress well. MPEG works by studying differences between pixels between frames. If there's no difference from one frame the next, then the same video information can be used for two frames. If the pixels between two frames are different, then the video information for each pixel of each frame must be stored - double the storage space.

The black bars above and below the image are (for all intents and purposes) the same black throughout the film, thus out of roughly 200,000 frames (SW is @178,000), the same video information can be used for all the black pixels. Since the anamorphic video has less black area, there's more actual changing video that must be analyzed and compressed.

I hope that made sense.