This is a huge story, and they're right that it has to be completely humiliating for Melania Trump. At minimum, it exposes her as someone who was willing to get up and give a speech about her life that was written by someone else, which wasn't obviously true to her life.
However, while everyone shouts at each other and tries to gain partisan points, let me suggest that this was a hoax. The evidence is the "Rickroll" in the middle of it.
Now as everyone knows, the "Rickroll" is an internet hoax created and popularized by 4chan pranksters. At least some members of Anonymous, which is linked to 4chan (and indeed commonly thought to have grown out of it originally) have declared war on Donald Trump, although the group's main channel has rejected the call.
Still, my guess is that some of these hackers got access to the Trump campaign's data -- through a hacked private email account, it could easily be -- and altered the speech in a way that was guaranteed to be humiliating to Ms. Trump. The "Rickroll" in the middle is a kind of signature, then, so everyone will realize how clever they were.
If I'm right in that guess, it was a devastating move. By the time anyone picks up on it, the news cycle will be over and she will have been both publicly humiliated and likely permanently damaged as a campaign asset.