How-Know Projekt : https://www.youtube.com/channel/UC_i3zU0FJXG6S_juBMiBpzQ - Prgogressbar and others

bitcoin a technologie: https://youtu.be/5opVvBjlcMY - Students of liberty

bitcoin by Jenda Hrach : https://www.youtube.com/watch?v=b8cHBAdfHQs