The rules were explained and the correct answer was one of the possible choices. No S&P problem.
But 0 is not actually one away from 9. One might
infer that the possibilities for a 9 would be 8 and 0, but I wouldn't blame someone for either thinking it must automatically be 8, or just being flat-out confused. 9+1≠0, so while it's poor logic and shouldn't be done at all, I think contestants need to be explicitly told how nines and zeros work, and in this clip the contestant was not (even though his guess and the correct number were both 8 so the issue never came up).
On the topic of Lucky Seven, I think that skipping from 9 to 0 would be acceptable if the numbers were revealed in reverse order. Say, for example, I guessed 9, and the correct number was 0. I could have been thinking the price ended in -89, when really it ended in -90, so I would really be only $1 off.