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Okay, I'm not 100% sure if I follow you on this, but it's a bonafide subdomain that's contained within the folder structure of the primary tld.
The precise path works like this: /var/www/virtual/topleveldomain.de/videoportal/htdocs
... where videoportal is the name of the subdomain with the vshare files.

But online the subdomain is accessed, as explained, via www.subdomain.fromtopleveldomain.de

Of course the topleveldomain.de also has its own htdocs folder for just the files that the tld uses.

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