Each clip records the real agent-deck binary running real commands in an isolated sandbox (scratch HOME plus a per recording tmux socket, so no live session is ever touched). Nothing on screen is scripted text: the echobot reply you see is the genuine agent output, read back with session output. VHS only supplies the paced terminal and the WebM encode. These are an on demand artifact, not part of the release gate. The pass or fail signal lives in capability-dashboard.html; these videos let you watch the same flows run.
Launch a real echo session, send the token PING-DEMO-7f3a, and the agent echoes it back as ECHO:PING-DEMO-7f3a in the pane.
A single agent-deck launch adds the session, starts the pane, and sends the message; the registry row appears running and the agent has already echoed the launch token.
Start a session, see it running in list, run session stop to tear down the real tmux pane, and watch the registry return the row to stopped.
Forking an unsupported session is refused with a clear error and creates no child row. The full fork happy paths need real Claude or Pi session data and are documented nightly gaps.