Publishing a long phone video could end in "the connection dropped" with nothing published: Instagram, Threads and X need the video re-encoded to their specs, and that work took longer than a web request is allowed to live. Now the post is recorded the moment you click, the composer says so with its number, and the server prepares the video and asks the networks from its own process within two to five minutes. The queue shows the post from the first second and updates as the networks answer.