Your post has little to do with what was said in the video. By German law insulting someone is a crime, it does not matter if they are a politician.
https://www.gesetze-im-internet.de/stgb/__185.html
Die Beleidigung wird mit Freiheitsstrafe bis zu einem Jahr oder mit Geldstrafe und, wenn die Beleidigung öffentlich, in einer Versammlung, durch Verbreiten eines Inhalts (§ 11 Absatz 3) oder mittels einer Tätlichkeit begangen wird, mit Freiheitsstrafe bis zu zwei Jahren oder mit Geldstrafe bestraft
In Englisch:
The insult is punishable by a custodial sentence of up to one year or a monetary penalty and, if the insult is committed publicly, in a meeting, by disseminating content (Section 11 (3)) or by means of an assault, by a custodial sentence of up to two years or a monetary penalty.
Also, since the interviewed are prosecutors they an interest to make the law sound as harsh as possible because that is literally their job. There are a bunch of laws that can overrule this law. Freedom of speech overrules this in most cases, unless the only point of what you are saying is to degrade someone. For example you can say “I don’t like ‘policy’, ‘politician a’ is such a fucking idiot for suggesting it.” But you can’t say “‘Politician a’ is such a worthless piece of shit and they should kill themself”, because you aren’t criticizing just degrading.
Another thing to consider, is that AFAIK this law has been around since 1953, so Germany was technically not a sovereign state as the Bonn-Paris conventions would not be signed until 1955, so US had a non ignorable influence in creating this law.