The author should note that the homepage at https://sequinstream.com/ does in fact claim that Sequin supports "Exactly-once delivery" under the "Key features" heading.
> Exactly-once processing: Messages must be ack'd after they're delivered.
> For example, imagine when a worker processes a message, it performs
> a side effect like sending an email. It very well could receive the
> message, send the email, but then due to a network error fail to
> acknowledge the message.
It was a good video until the RST.