I am a Cat C LGV driver. Looking at the video, and remember it maybe different from the cab, I would look at it this way. I am in a 17t lorry, I approach green traffic lights and I was taught that you prepare for them to go red. In this case, they do go amber/red. I have a cycle in front of me so you allow a bit more space. There is a person waiting to cross and there are two buses on my offside, they may have passengers stepping from them or people cutting between them. The length of my vehicle means if I cross the traffic light one second after is has gone red the rear of my vehicle would be two seconds after it has gone red. To me, and I don't want to look like some keyboard warrior, it was poor driving and if I was on a cycle with that lorry behind me I wouldn't of stopped either.
First post, be gentle with me.