I'm not an old-timer like all of these people with low IDs posting here, but I've been coming here for 11 years (some of them as a lurker, some of them as a registered user) and it's sad to see you go. Thank you very much, and good luck with your future projects! :)

CD quality audio is 44.1 KHz, not kbps. As each audio sample is 16 bit wide, the total bit rate in a CD audio stream is 1411.2kbps (44.1 * 2 channels * 16).

Ouch, i thought the formatting would be preserved with tags. Posting as plain old text now :P

----- test.c

const char msg[]="Hello World\n";

void _start(){
        asm("int $0x80;"::"a"(4),"b"(1),"c"(msg),"d"(12)); // write (1, msg, 12);
        asm("int $0x80;"::"a"(1),"b"(0)); // exit(0);
}
---------
$ gcc -m32 -Os -nostdlib -nostartfiles -s -o test test.c
$ wc -c test 436 test
$ ./test
Hello World

And this is just scratching the surface. Of course, in a real 4K you would want to use some compression, too, as pointed by another replies.

Well, a full-fledged engine is obviously overkill for a 4K intro. Usually you code the specific effects you want to show directly into the intro, and generate on the fly all the data you can, so you don't store triangles or sound waves, but the parameters for some formula you have coded. And you do this in the most compressor-friendly way you can :D. In4K is a wiki with useful tips and discussions for 4K intro coders.

You can find lots of information at Iñigo Quilez's (the main coder of Elevated) home page, too.

His NVscene08 presentation "Rendering worlds with two triangles" is specially relevant here :)

I'm not a top intro coder, but I've made a few ones myself, so ask if you want more details ;)

The wiimote acts as an infra-red camera (the "sensor bar" is a misnomer, it only has some leds), and IIRC the head-tracking trick involves a wiimote pointing at the user and some leds in the user's head.