The mod allows you to track entity movement (excluding players). Can be used to debug various contraptions (TNT cannons, falling sand entities, etc).
Trace color, thickness and delay can all be customized via the standard GUI config. All command have autocomplete (press tab).
Modpacks: you can freely include any of the mods in your mod pack if the modpack is free (public or private). Mentioning me as the author is appreciated but not required.
Youtube/Streaming: you can monetize any videos you produce with the mod.