revert video

_toc.yml

@@ -4,7 +4,7 @@
 format: jb-book
 root: intro
 chapters:
-  - file: introduction/videos.ipynb
+  - file: introduction/Intro.md
     sections:
     - file: introduction/ex_01_introduction_to_pyiron.ipynb
     - file: introduction/ex_02_creating_structure_databases.ipynb

introduction/Intro.md

@@ -4,6 +4,8 @@
 Density functional theory for computing properties of materials (background and intro to DFT, key parameters and popular codes, basic properties and computation principles: formation energies, defect energies, elastic moduli, phonons)  
 Jörg Neugebauer (MPIE Düsseldorf)
 
+<iframe width="560" height="315" src="https://www.youtube.com/embed/li7GL1KeaYs" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+
 ### <font style="color:#B71C1C" face="Helvetica" > Tutorial II </font>
 Workflow management with pyiron (motivation, intro to workflows and pyiron, computation of the properties that were introduced in the first tutorial with pyiron)  
 Marvin Poul (MPIE Düsseldorf)