I bought the 65" Curved 9000 4K Samsung last week from Best Buy. I e-mailed them or really filled out their online rebate form on which you had to include the set's serial # and a copy (Jpeg) of the store's receipt. Initially the site would not accept my request citing an invalid S/N which I had copied from the UPC label on the box. I e-mailed them about this and it turns out that the S/N had an extra character on the back of the set label, so after I included it it was accepted.
BUT today, I received an email from Samsung stating that my rebate request had been rejected as filled out on their site, and that I had to fill out a rebate form to be MAILED to them with the original store's receipt and cutting out the UPC label from the box. Luckily, I had not thrown out the box yet.
If they accept this they state it takes 10-12 weeks for the hard drive with the 4K content to be sent.
Hope this helps.