: Document the assembly and testing of the LISA (Laser Interferometer Space Antenna) Engineering Development Unit (EDU).

: Often denotes a file number, an age, or a specific version in a series.

where creators use "SS" (potentially for "Secret" or "Simple") as a prefix.

: Refers to a video file (.mp4) documenting the labor, testing, or "beauty shots" of the hardware being integrated.

The "MP4 Work" moniker suggests it’s designed for people moving in front of cameras (fitness instructors, dancers, or set crew).

Yes — on sale or as a multipack.