ntsc() is the picture as it came down a composite cable. Brightness and colour travelled mixed in one signal, and the television could only part them roughly: colour smears sideways while brightness stays sharp (bleed), the colour that leaks back into brightness crawls a little every frame (crawl), and sharp edges in brightness are mistaken for colour, which makes rainbows on fine detail (artifacts).
Artists of the era drew for it: dithered stripes that a cable blended into a solid colour. Some old art only looks right through this.
It belongs right before the tube, which is the order the signal travelled in. Press 1 to 3 to toggle each part, T to put a crt() after it, and Space to switch it off.