Very, very angry. Sometimes even though they get that it's a joke.
What we have decided we really like about this video is not the acting. Actually, we're not sure whether they're acting like they're terrible at acting or are actually that terrible, but it doesn't matter. Either way, it's not the best part. The best part is that real effort has definitely gone into getting so many details about the cars wrong. The video was clearly made to troll fanboys of both the Mustang and the FR-S, as well as possibly Jeremy Clarkson.
Some of it is a bit over the top, satire is best when it's subtle, but it's still pretty effective trolling.