Used to be he'd wait a decade or so before reviewing these. There'd be retrospect and actual footage from the films to use in the review for reference.
There still is actual footage from the films for nearly all of his reviews...but, even if he waits a decade, there's still gonna be some films that he won't be able to show any scenes from(as a few of his reviews being taken down shows), that's just the way it is in some cases, unfortunately.
He does need retrospect to work though. Thats why I never watch these. A film may seem great or awful on early glance but time can change that perspective. I use to love Dark Knight Rises, but as time has gone on, I've seen its flaws. Same for Skyfall.