Now that's just mean.
I heard "Han skrattar fult". Would that be the same pronuncation if spoken fast, and would that be proper Swedish?
They're certainly close! But it's not the exact same. I'm confident most natives would hear the difference virtually every single time.
I heard exactly the same. The only difference in pronunciation seems to be the ä in är. Luckily in this sentence it does not really change the meaning of the sentence. I think it usually is clear from the context.
That is exactly what I heard too.
A more natural English translation would be "His laugh is ugly", rather than "laughter" (western US English speaker here)
I much agree with MarksAaron, and think that "laugh" should be the preferred noun.
"U" in "fult" ends with some labial sound like a little, hidden "b", right?
Not really, but the following links does get a hint of that quality by definition, I suppose.