No track time, just trying to learn before going on track.
With my technology, I can't see anything displayed in the mirrors from the video.
What I see:
From about :27 after the gentle right curve, it appears you're keeping to the left rear of the (Ranchero?), and, on the track I see just about the whole shadow of that vehicle to your right, and you're heading into the sun, so it's a long shadow on the track, and for a comparatively long time.
Contact is at about :41, in the curve, after your abrupt position change from: well behind and to the left of the leading vehicle to: the inside of the curve. I can't clearly tell, but it looks like prior to the apex.
So for about 14 sec. it initially appeared to me that you were leaving a lane behind the leading vehicle, perhaps for a trailing car, or one that was already there next to you, perhaps half a car length behind your front bumper, or at about your rear wheel well. I've been entertained by Lemons stories about going down the track 2-, 3-, and 4-abreast, and I'm assuming that includes corners, so that colors my understanding of this incident.
One scenario proposed is that someone unreasonably dove into that space, and I can certainly imagine that happening. _I_ wouldn't do it, but I'd be aware someone might, and I'd be pretty exasperated with someone who would.
In the initial post describing the contact, there was no story line, or description, as to where the inside vehicle _was_ prior to the contact.
You also describe your concerns because of the sun whether the vehicle ahead of you would see you if you decided to pass them.
Absent another explanation, one scenario I could propose is that a vehicle trailing on your right decided you saw them, were deliberately leaving that lane for them, and they would proceed on that basis. When they took advantage of the slowdown for the curve to gain some relative distance, your abrupt position change left them no room, and as they were trying to avoid you on the inside, they ran out of room - and mostly if not completely off the track - and decided to return to the track rather than being pushed into the barriers by the avoidance, with no impact damage to explain why they went into the barrier.
This might explain why there was no damage to your rear bumper, and only the rear-wheel area on your car.
So please help me learn this racing thought process.
When you looked in your mirrors - you said you looked in your mirrors and didn't have to turn your head to do so - where was the inside vehicle in relation to your vehicle? How long was it there? What was the rate of closure? Or, did they give up the inside position next to you and then try to get it back too late? Were they clearly behind you to start out with, and, did you have clearance when you moved to the inside; but they didn't slow, and came over the grass to move you out? I don't have enough information to understand what happened.
On the public roads. I was hit right behind the left-front wheel well making a left-hand turn, by someone who didn't maintain their lane on the inside. In this case, there were two _CLEARLY_ marked left-hand turn lanes, and my choice was drive into the curb trying to avoid the inside guy who abruptly decided to switch from the inside lane [him] to the outside lane [where I was] at the last MOMENT - 3/4 of the way through the turn, or to get as far over to the right as I could hoping he'd get back into his lane. And just to be clear - I started out ahead at the light, and was directly ahead of him at the contact. I think one more millimeter to the right and I'd have curb rash on my outside tire and wheel. His wife was very apologetic. He was also, but a little later.
I look forward to advice and more information.