It's a shame that this law still doesn't apply to YouTube
If Germany is anything like Canada and other countries, applying public broadcast laws to YouTube would be a monkey's paw deal. Sure you might get tighter control over advertising, but youtube would also be forced to do things like show you x% of content made in your country/language, resulting in state mandated control of the content you see online and potentially limiting/warping international audiences for content creators, and potentially other ramifications I'm not considering.
Now if they made a law specifically for youtube and other online video platforms that dealt with advertising in that context, that would be a different story.