: This is a shorthand for t.me , the domain used for Telegram channels and groups.

. This combination of terms appears to be a composite of several disparate components, likely related to non-official file sharing or social media links. Telegram Messenger Analysis of Components

Here is an interesting blog post structured around that cryptic filename, exploring the intersection of digital archiving, "mystery" media, and the evolution of content.

Based on the structure of the string, here is a breakdown of what the components likely represent: xxxmmsub.com