Yikes (at the quality of that video)
There's absolutely nothing in that video that would alter my opinion.
If I have time tonight I'll do an image beside image gameplay comparison of Brands Hatch..so at least it's a sim for sim. Horizon 3 during gameplay on PC would be an unfair comparison.
I'm Back* All shots are gameplay. Look at these at full res.
Gran Turismo: Sport
Forza 6
For those that need help seeing clarity and textures/detail during gameplay...
Both Images Forza (left) / GT:S Right
Like I said, at best on par..and even missing things like grass detail or a defined fence for example...not to mention a very blurry image. HOWEVER, it's a beta, and it could improve...but my opinion stands on the beta. Note: FM6 even has the glinting sun off the back of the car.
Whatever, I came back and posted like for like (as close as I can get .pngs) above after you made the above post. Detail and clarity isn't something you can argue...if you don't see it, then I can't help you
Hopefully you come back and scroll up to see me doing what I said I would.