Question: I am looking for a solution to control my computer mouse just with my hands and a webcam. The goal is to combine it with voice input to let me move more freely in front of my desk.

It should support the usual mouse actions:

* position mouse pointer, left click, right click, middle click, scroll up, scroll down
* optionally: scroll left, scroll right

Answer: 
[avidemux](https://en.wikipedia.org/wiki/Avidemux) can add .mkv files at the end of each other.

Usage: Open the avidemux GUI, drag-and-drop the first .mkv file, then the second, then press "save" and enter the filename you want for the output file.

The input files must have the same size and encoding.

Available for Linux, Mac, Windows.

It is free and open source. It uses ffmpeg's libavcodec library under the hood.
This is what I use

<https://www.fosshub.com/MKVToolNix.html>

You can see the result here

<https://www.youtube.com/watch?v=2_TCmWRUQrI>

Basically a 3:20 video is combined with a 30 minutes video

Notice to do this you need to ensure you that you append video to another video

The first time I am doing it I just combine 2 video. The result is one mkv files that contain 2 chapters.

No I want to append one video one after another.

[https://www.macworld.com/article/223409/how-to-combine-two-dvds-into-a-single-movie.html#:~:text=Launch%20MKVToolNix%20and%20in%20the,navigate%20to%20the%20second%20movie](https://www.macworld.com/article/223409/how-to-combine-two-dvds-into-a-single-movie.html#:%7E:text=Launch%20MKVToolNix%20and%20in%20the,navigate%20to%20the%20second%20movie).

> 
> Launch MKVToolNix and in the window that appears, drag your first
> movie file into the Input Files area (or click the Add button,
> navigate to the file, and then add it). Then click the Append button
> and navigate to the second movie.
> 
> 
> 

That is how. Do not simply add 2 videos.