Can add some context to those not familiar with the area. The camera is on the American shore, Canadian shore is the far side. Current generally runs left to right in the camera angle, and in that area a curve in the river means higher current in the American side, about 4-5kts.
The PHYC is basically at the right of screen, behind the white-cubeish building. Normal protocol for leaving PHYC, going up the St Clair River to Lake Huron is to hug the Canadian shore, and realistically, under motor. Even then most sailboats are doing 1-2kts SOG at times. This is Lake Huron funneling into the St Clair River after all... all the water of the Great Lakes goes through here!
Based on the beginning of the video, Intrepid looks to be close-hauled, heading almost due East... hard to say exactly based on camera angle, but watching it several times it looks clear they are not going North, but rather cutting across the river towards Canada. So they shouldn't be fighting the full current, but regardless, the water around them is moving pretty good.
Don't know what they were doing... if heading towards Lake Huron, they are too close to the American shore. If heading back to PHYC, which appears what they do after the near miss,don't know why they would have been heading East. Wind would have been North-East... when they gybe that seems to align with heading West towards the American shore.
It's clear when they gybed, they got the current and wind both working in a direction to move them out of the way, don't know why they wouldn't have headed towards the American shore earlier for safety... unless they really were trying to sail to Lake Huron and thought they could get to the East faster than they could.
Those freighters come-up fast in that area!