This is the most cryptic part. In the context of early piracy forums and Telegram channels (which started gaining traction around 2015-2016), "OK" was often used as a verification or "all good" signal. Alternatively, it might be a fragment of a filename (e.g., Ok.Hindi.2015.720p.Khatrimaza ) or a misremembered prefix. Some users interpret "OK" as part of a URL shortener or a specific uploader’s tag from that era (e.g., "OK_Scene").
The "nostalgia" for 2015 files is essentially nostalgia for guaranteed compatibility with older devices. ok khatrimazacom 2015 link
Khatrimaza is a well-known piracy platform that frequently changes its domain names (like ) to evade legal bans and copyright enforcement. In 2015, these sites were highly popular for offering free downloads of Bollywood and Hollywood movies in formats like 300MB MKV. This is the most cryptic part