Given the nature of this string, it is likely found in niche, user-generated, or specialized media communities rather than mainstream streaming services. Potential sources include:
The string you provided, "juq050 engsub023501 min fixed," appears to be a specific filename or metadata tag associated with adult video content rather than a scholarly or scientific paper. Specifically, is a production code for a title featuring the actress Ayumi Kinoshita juq050 engsub023501 min fixed