They might have encountered this in a video title or a product listing and want a story explained around it. Since there's a reference to subtitles, perhaps they saw a video about a device, and now they need more information. The numbers are a bit unclear but could be part of the product model or a video identifier.
I’m not sure what format or purpose you want for this draft. I’ll assume you need a concise English-subtitled (engsub) description/metadata/title text for a portable video file named "meyd506 engsub015643 min portable." Here are three brief options—pick one or tell me which style you prefer (formal, casual, or technical): meyd506 engsub015643 min portable
If you find a file with this naming convention, do not try to upscale it. The damage is done in the compression. Instead, enjoy it for what it is—a miracle of mathematics that allows you to carry a 2-hour movie in your pocket. They might have encountered this in a video