[bluegoof]

@Alesn:
Aleši, já jsem udělal přesně toto nastavení a funguje 1920x1080 za všech okolností.
Je to zde: https://koditips.com/setup-use-youtube-kodi-addon/

To enable the playback of HD videos in the Youtube addon, you MUST have InputStream Adaptive and RTMP Input enabled:

From the Kodi main menu, navigate to Add-ons > My Add-ons > VideoPlayer InputStream
Click on InputStream Adapative and then select Enable.
Click on RTMP Input and then select Enable.

Configure InputStream Adaptive:
Ignore Display Resolution: enabled
Max. Resolution general decoder: Max
Stream Selection: Auto
Min Bandwidth set to 10.000.000

Configure YouTube add-on:
MPEG-DASH -> Use MPEG-DASH: enabled
MPEG-DASH -> Use for videos: enabled
MPEG-DASH -> Use for live streams: enabled