“Trackmo” is a word that describes a certain type of demo of the Amiga era.
Big demos used to be called “megademos”, which were an assortment of routines, many times each with its own music, that were presented to the viewer one after the other or selected by the user on whichever order they might wanted to watch them.
The trackmo is as big as a Megademo and in many ways similar (one routine after the other) but it’s played like a videoclip, in one shot, under one or two soundtracks, and usually has sound coordination. These were very popular in the Amiga and many of the biggest classics are of this format (like 9 Fingers).
C64 demos are not usually trackmos but in the late years they have started being so, and the name just stuck. Here’s a very Amiga-inspired trackmo from the FST crew, released at Assembly 2010