Exactly, the RUFs are easily confused with Porsches (so much so that in the early GT games people though RUF was made up and only a gimic to slide in Porsche under the licensing radar) (what can I say, teenage friends of mine in the mid '90s, who would guess they didn't know about companies like RUF).
As for the gameshark, I doubt the video will show (especially since I don't recall a way to view that movie on demand).
A good test might be to race a single event from professional hall (or even a full series, a short one would do). If you were to beat one of those the video might show. That's just a guess though so don't count on it.
Also, since you've got the gameshark game save, you probably have lots of cars and all the licenses (if not cheat those in as well). With that in mind, just beat all of the races in "beginner" and "professional." Should take long with the equipment you have. 👍
Finally, just a thought here but... Are you sure it was video and not a replay? (never know so I thought I would ask)
I mean, GT4 is good but I don't think it's video-good. None the less I thought I would ask.
