I´m not so sure about this whole story. Fr. Lingen has a very dubious reputation and hardly anybody takes him seriously. So far he only brought ridicule to the sedevacantist position.
On the other hand it is true that one cannot style oneself a Catholic Priest in Germany easily. Due to the Concordat of 1933, the priestly title and garb is reserved to the Catholic clergy. As sedevacantist clergy acts independently from any official structures, they are not considered part of the Catholic clergy (in ordinary times, this would be a rather good thing, of course).
But I have never heard that somebody gets imprisoned for this reason.
I haven't seen the video because my dial-up connection simply stops downloading from gloria.tv after about 4 seconds is downloaded. I get part of the picture from the comments, however.
While what is being discussed seems far-fetched, I also recall that Bishop Williamson faced possible jail time for merely stating that he
doubts 6,000,000 Jєωs were killed by nαzι Germany. In view of this, is it really all that incredible that a sedevacantist priest could, if he were very outspoken, be jailed in Germany because he is not "recognized" as a "true" Catholic priest?
Americans tend to view the world with American eyes. Europeans (as well as Canadians, Mexicans, and South Americans) simply do not look at the world the same way. Just as Americans tend not to understand a lot of history because the fusion of religion and state is such an important aspect in understanding history, Americans seem to automatically assume all modern peoples start from their own perspective of the "correct" relationship between church and state. Frankly, Americans are, for the most part, the only people who hold such an absolute view.
Without more eyes on the ground, we won't know for sure that this man was not actually jailed, but the very idea should not be summarily dismissed either. Pyrrhos has made a very good point about actual German law. The accusation that a priest who is not officially recognized as a priest could be jailed in Germany is not, I think, so incredible as to simply dismiss the claim.
There seems to be more skepticism about this claim than the claim that G.W.Bush blew up levies in New Orleans and planned the 9/11 attacks.