CBP applies a substantial transformation test: the country where the medium undergoes the process that imparts its essential character — typically the recording or coating step — is generally deemed the country of origin. Importers using multi-country supply chains should obtain a binding ruling from CBP to avoid origin disputes at entry.

Yes. NAICS 334610 encompasses establishments that manufacture blank magnetic and optical media as well as those that reproduce (i.e., mass-duplicate) pre-recorded content onto those media, such as CD/DVD replication facilities.