Hello, I have silly question. I never understood this: "Any and all saved replays (F3) used during the run must be recorded earlier on within the same run. " how does that work, can't you just run the game with like wsplit and stream it? or is that like a video proof for submitting, since you don't have obs or something?

Replays have nothing to do with the way OBS records the gameplay. They are an in-game feature that allow you to watch the last few seconds of game-play. So don't let that rule confuse you. :) They can also be saved and played back with F3, hence the "name" "f3 replays". When you play a replay, then the cars appearing in it are more likely to spawn in the "real world" some time after that. The "replays have to be recorded earlier in your run" means that you can't record a replay that is full of sports vehicles before the run starts and use that every time you need a fast vehicle.

Also another question, what's the best resolution/settings to use, if you're lagging a bit? I use 1920x1080 32, but my mouse is lagging as in being slower than usual...

if your mouse is being slower, higher the mouse sensitivity