Yes, traditionally A4 is bus gates for domestic departures, and is fully kitted out with the requisite cameras. But nowadays so is one of the A10 gates, so it’s a bit more of a mix than it used to be. One of the B gates is also frequently used for US departures from remote stands, as that’s where the security guys are based (but confusingly, this doesn’t prevent US departures being A10 or A18 on occasion).