"So, I went to a little wedding a few months ago. It was the royal wedding, actually, not such a little wedding," she quips in the video that she posted to Instagram on Friday. "What do you wear to a royal wedding?"
While the former Spice Girl knew that she wanted something "appropriate, something feminine, something that I felt comfortable in," she didn't want to shy away from "a little bit of edge."
"So, I designed this dress that has this really beautiful D-ring neck detail, because I love the toughness," Beckham explains. "It's very, very slimming -- that is always key. A nice slash down the front to get some skin out, makes it feel feminine and makes it feel quite sexy, but still appropriate."
Another sexy aspect of the dress -- the open sleeves -- was mainly incorporated to combat the weather.
"Then we've got these slits in the sleeves, so when I wore it I had it open, so I could get some arm out. It was the hottest day that I think England has ever had," she recalls. "I was sitting in the car for two hours before I got to the royal wedding and I felt cool and comfortable, so it's perfect for summer."
Victoria attended the royal wedding with her husband, David Beckham. The couple celebrated their 19th wedding anniversary earlier this month and, in a sweet post, the 43-year-old former soccer pro called his wife "the most amazing wife and mummy."
The touching tribute came after divorce rumors began circulating around the couple last month. "[Victoria and David are] not divorcing or splitting, and reports to the contrary are false," Victoria's rep told ET in June. Another rep for the couple concurred, saying, "It is absolutely not true."
Here's a look at the pair at Meghan and Harry's nuptials: