OK I have a question.

I booked a frequent flyer ticket on VS and when I clicked through to pick a seat it tried to charge me the $70 each way (so I cancelled the booking)

But now I see this on Delta. com

If you are a SkyMiles® Diamond or Platinum Medallion®, you can select seats for all your party (so long as you are in the same booking) up to 336 days before departures free of charge, you may select an Extra Legroom or Exit Row Seat for yourself free of charge and standard seats for the rest of your party.

So does anyone know how this works?

Thanks!