This article states that:

Warner Home Video will include two downloadable digital files on its Dec. 11 DVD release of Harry Potter and the Order of the Phoenix.
The latest Potter installment will allow DVD buyers to download the film to a PC or a portable device, making Warner the first studio to so marry physical media and downloads.
“You can buy the DVD and have the option of the digital copy,” said Wuthrich. “This future-proofs the format for consumers.”

The DVD will be released December 11th in the US.