OK, but your only avenue to attempt to get the PCN cancelled, is to first submit representations to the council that whilst there is an adavance warning of a width restriction, there is nothing about the bus gate. They will inevitably reject those reps. You then have the choice of paying the PCN, (the council will probably re-offer the discount if your reps were sent within the discout period), or registering an appeal at the Traffic Penalty Tribunal, claiming the signage is inadequate to advise motorists of the restriction. My view is that you would lose, because the signs are approached head-on and visible from some distance away.
Did you actually know what the signs meant as the video shows you driving through them with no hesitation at all ?