video_controller.ex

defmodule CatcastsWeb.VideoController do
  use CatcastsWeb, :controller
  
  alias Catcasts.Videos
  alias Catcasts.Videos.{Video, YoutubeData}
  
  plug :check_video_owner when action in [:delete]
  
  ... # Code removed for readability

  defp check_video_owner(conn, _params) do
    %{params: %{"id" => video_id}} = conn

    if Catcasts.Repo.get(Video, video_id).user_id == conn.assigns.user.id do
      conn
    else
      conn
      |> put_flash(:error, "You cannot do that")
      |> redirect(to: video_path(conn, :index))
      |> halt()
    end
  end
end