@Eisblume
You need two things:

• first: a modules which is able to stream 100Sec Tagesschau, i made a fork see MMM-Podcast2
• second: the right config (i posting only the relevant part)

....
{
			module: 'MMM-Podcast2',
			config: {
				// See 'Configuration options' for more information.
				omxargs: ' --win 0,0,1920,1080  -o both '
			}
		},
{
			module: "MMM-Navigate",
			header: "Navigation",
			position: "top_right",
			config: {
					Alias: [
						'Tagesschau 100 Sekunden',
						'Herunterfahren'
					],
					Action: [
						{notification:'BUTTON_PRESSED',payload:''},
						{notification: "REMOTE_ACTION", payload: {action: "SHUTDOWN"}}
					],
					GPIOPins: [26,20,19]//rotary cw, rotary ccw, rotary press (BCM Numbering)
					},
		},
...

AxLED

@Eisblume
No Problem, i am glad it works for you now, so you also did your first coding experiance.

AxLED

@Eisblume
Thanks for your reply, i tested at my pi with disconnected ground cable, but there is no press, cw or ccw working at all.
My last ideas:

• can you messure your 5 cables if maybe one is interrupted
• maybe there are two versions of KY-040 on the marked, i have this one Amazon
• is your second rotary encoder shows same symptoms?
• did you connect + of rotary encoder to 5V once (which would be wrong and maybe damaged your GPIO PINs/chip)?

AxLED

@Eisblume
I tested wih modules of your config.

My testconfiguration:

• Raspberry Pi 1
• MagicMirror v2.7.1
• npm v6.8.0
• node v8.9.0
• no electron (as i dont run/installable on Pi 1), i run node serveronly
• display: Webbrowser

My rotary encoder works as follows:

• Seite blättern (press works and gives a red frame an a lock sign, cw an ccw dont work, as MMM-Pages isnt part of your config)
• News (mehr/weniger Details) (press works and gives a red frame an a lock sign, cw an ccw works)
• Test notification (press works, no cw or ccw functionality by design)
• News - mehr Details (press works, no cw or ccw functionality by design)
• News - weniger Details (press works, no cw or ccw functionality by design)
• Neustart MagicMirror (PM2) (dont work in my testconfiguration, as i dont use PM on RPI1)
• Neustart (press works, there is a pop up notification to press twice for reeboot, requires MMM-Remote-Control)
• Herunterfahren (press works, there is a pop up notification to press twice for shutdown, requires MMM-Remote-Control)

Two ideas:

• wrong cabeling, here are the 3 pins for CW, CW and PRESS of your config.js (GPIOPins: [26,20,19])
  
• messed up setup, try to save your config and reinstall raspian an MM

Greets

AxLED

@Eisblume
Please post your config and make sure your private keys are x-ed. So i can try to copy your setup to my test pi and maybe find out whats the reason. That your rotary encoder generally works is good to know.
AxLED

@Eisblume
I found the line in node_helper.js, its line 35

const C = new Gpio(self.config.GPIOPins[2], 'in', 'both',{debounceTimeout : 20 }); //BCM Pin 19

Here you can try to increase/reduce the debounceTimeout between 10 and 50 (in steps of 10) and see if there is a difference for your “pressed” problem.

AxLED

@Eisblume
Conflicts with other modules are possible, but i dont think so, because press on cw/ccw works. You can try to change debounce time in node helper (i think, i am not sure about as i am on the road right now). I will check for the final line in node helper and let you know if i am in front of my computer.
AxLED

@Eisblume
So the pin is correct. Some ideas.
Press contains two operations, pressing and release. Did you try press and release in different speeds?
How long are your cables between rotary and pi? Could also be a debouncing problem. Which pi are you using? (I tested the module on pi 1 and pi 3).
AxLED

@Eisblume
You can also try to put clockwise or counterclockwise signal on pin 19 for testing, so cw or ccw should send the press command. So you can make sure if press switch of your rotary encoder is bad.
AxLED

@Eisblume
Did you use the right Pin (either in config or on the pi) for the ‘press’ signal of the rotary encoder?
Is the module MMM-Remote-Control installed and working?
AxLED