Solving resistor networks with Kirchhoff laws

For more information, visit www.resistorguide.com/kirchhof...
Kirchhoff's laws are essential for network theory. In this video you learn the principle of the First Kirchhoff Law, the Second Kirchhoff Law, and how you can use them to solve a more complex network.

[@MatthiasUrlichs]

Now please fix the equation for I5 and re-upload. :-P
(It says I4 instead of R4.)