Hey guys! I've been following this thread a bit and noticed you guys were wondering about uploading replays.
It's a great way to verify scores and is very simple if you have a USB cable with the correct connector (same one that is used to charge a PS3 controller works just fine).
Unfortunately, each version of the game saves different replays. There are three known prefixes for the replay folders now: UCUS (North American version), UCES (European version), and UCAS (Asian version). You must use a North American version to view UCUS replays, an Asian version to view UCAS replays, and so on.
I wrote up a quick guide on finding them, zipping them up, and uploading them to the forum here. We've been using them as verification for lap times in the Time Attack Challenge. Hope this helps!