Every seat is two URLs: the show and the sandbox

Your agency sells a two-day corporate training. Each seat gets two URLs. The first is the show: the instructor's display, captured once by ffmpeg, fanned out through a pipe to every trainee's ?video tab. The second is the sandbox: the trainee's own container, its own desktop, cloned from the course snapshot before day one.

Watch on the left, do on the right. When a trainee wrecks their environment: which is the point of a sandbox: it's one container, theirs, restored from the snapshot in seconds.

Training platforms price per seat for the broadcast, then per seat again for the labs. Here the broadcast is one encode, and the labs are containers on the flat-rate server you already rent: idle ones cost almost nothing.