You got a link to your source on that?

Merriam-webster says mousquet came from the Old Italian moschetto meaning a small artillery piece. It’s also a term for a male sparrow hawk. Which there was a traditio of naming weapons after animals.

https://www.merriam-webster.com/dictionary/musket

The Wikipedia page for musketeer says this:

The Musketeers of the Guard were a junior unit, initially of roughly company strength, of the military branch of the Royal Household. They were created in 1622 when Louis XIII furnished a company of light cavalry (the “carabiniers”, created by Louis’ father Henry IV) with muskets.

https://en.m.wikipedia.org/wiki/Musketeer

So the term Musketeer comes from the fact that they are armed with muskets. I cant find anything about a mousquet being a place on the belt to hold stuff.

https://m.youtube.com/watch?v=E72crLQ1S4M&pp=0gcJCfwAo7VqN5tD

Was it this episode of the X-files?

https://90sflashback.wordpress.com/2015/07/05/the-x-files-1-4-conduit-sister-sister/

Mulder and Scully are investigating a girl’s alien abduction. Her little brother is watching static on TV and writing out binary on sheets of paper. Later, the pages are laid out on the floor in a big square. Scully goes up the stairs and looks down, revealing the pages were and image of the kid’s abducted sister.