The video was posted on YouTube today by ConceptsiPhone. The authors shows a 4.7-inch model with a redesigned home screen and an enhanced Fetina Display.
ConceptsiPhone also claims the iPhone 6 will have a 5-megapixel camera on the front and a 13-megapixel camera on the back that will be able to record ultra-high-definition 4K video.
Here's the video:
And here's another, slightly older video that appears to have been made by the same artist: