It is useful to know that HGVs do indeed have blind spots, but as a recently ex artic driver (did it full time for over 6 years and part time either side of those 6 years) I could pick the following faults with that clip:
Both mirrors are incorrectly adjusted; they are angled far too much towards the driver with the result that too much of the mirror is showing nothing more than the side of the lorry. Especially the lower (blindspot) mirror, about 50% of the mirror is showing the lorry! They should be adjusted so that they are only just showing the side of the lorry.
The clip doesn't bother to show that the driver has another mirror in addition to those 2, it runs along the top of the passenger side window and shows the area immediately below and a few yards outwards from the passenger door, which would otherwise be invisible.
The tractor unit of the lorry is turned at an angle to the left, and thus exaggerating the effect. If it was straight, the bikes would be visible. If the driver was properly carrying out a left turn manouevre then that situation would not arise - unless a cyclist ran up the inside of the lorry while it was turning.