Generally speaking, I think JA's original dialogue transfers so well to the screen. There are miniscule changes from the text and I think your've shown a good example. I saw that episode very recently but didn't notice the change (good spotting!) I think the script of P&P2 retains JA's own text in original form as much as possible. And it's sparkle is there. Notice the body language of Lizzy and Darcy during the dance. They're both abit stiff yet interweaving of their bodies with slight unbending implies their reluctant yet potent mutual attraction as they're gradually drawing together... Now you mention Mrs Bennet, I think she remains focused on the 'happy match' of Jane and Mr Bingley.Mr Darcy I daresay, remains in her disgrace. LOL!