Thanks for your answer.
In my case I think it isn’t the power supply, because I already use a 4A for the RPi (with usb grabber) and also a separate 4A for the LED stripe.
I have also used this power supply before on the well running RPi B+. Nothing changed, expect the RPi 2 and the OS (from Raspbmc to OSMC).
The RPi 2 is running well with hyperion and config using the usb grabber input, also on hyperion with kodi config and watching mediathek.
It is also running well if I’m running hyperion with video grabber config, switched my AVR/TV to OSMC and seeing the OSMC main menu and navigating or show mediathek content (the LEDs are shown like the video grabber source, because videograbber config).
It is equal how hyperion is running (kodi config or videograbber config), since I start a movie from my NAS the LEDs are starting with flickering.
I will test with other LAN connection…
Maybe it has something to do with hardware-/software transcoding…