So... here we go:
One Hit Pixel Article
Xbox.com Link
Game DVR, the Xbox One’s system for recording and uploading footage from users’ games will be restricted to Xbox Live Gold members.
This comes from an Xbox Live features page on Xbox.com, which lists features like SmartMatch, NFL on Xbox, Xbox One’s TV Guide feature and, crucially, its Game DVR feature as Xbox live Gold specific features.
We contacted Microsoft to get confirmation that Game DVR features would indeed be limited to Xbox Live Gold members. Microsoft responded, saying “I can confirm that Game DVR features will be available to Xbox Live Gold members only.”
One Hit Pixel Article
Xbox.com Link