Ja, das geht. Sogar relativ schnell, wenn man die Gruppe(n) kennt, in welche gepostet wurde und das Datum des Posts:
https://github.com/Tensai75/nzbsearcher
"Proof of Concept" for an NZB search engine that searches for a header directly on the Usenet server and then generates the NZB files.
The programme searches in each specified newsgroup for a configurable number of days backwards from a specified date. So if the approximate date the file was posted on Usenet and the newsgroup are known (e.g. from an Usenet forum post), there is a good chance that this program will find the messages and generate the NZB file for download. The program is mainly intended to search for very old Usenet posts that are still available on the Omicron backbone but have not been indexed by the known Usenet indexers.
Gruss, Tensai