In 2011, the "German traffic safety council" (Deutscher Verkehrssicherheitsrat, or "DVR") launched a traffic safety campaign with a series of traffic safety films, called "Sag' nein zu Hubert" ("say no to Hubert"). (archive of campaign site)
In this short film series, a man names Hubert goes hitchhiking and fools his drivers into unsafe behaviours. The series was available on YouTube until at least 2019. (2018 archive with thumbnails)
Now, the channel shows a 404 error and any video shows the generic "This video is unavailable" error message. There is no indication as to why the channel vanished, but it appears either the DVR voluntarily took it down, or YouTube purged old channels to save space. This channel was over eight years old at that point.