Note to cell phone leakers: please try and get decent video before you send your information out into the world. A YouTube video spotted by XperiaBlog does indeed seem to be Sony's latest phone, or at least a phone that looks a lot like their previous hardware and seems to be sporting a new version of the company's Android UI. Unfortunately there's little to be seen of the hardware itself.
What we can see is a short tour of some of the new interface functions on what is purported to be the D6503 "Sirius," expected to succeed the Xperia Z1 whenever it's announced. The user in the video pays particular attention to the Walkman music widget, a revamped lock screen, and refreshed camera apps. Take note of the music widget on the lockscreen: even in its minimized state, you can track to any point in a song, something that most music widgets can't do.
We've seen the Sirius in a few candid photos and a ton of screenshots, which show that the phone is probably a flagship and coming soon. Leaks indicate a 5.2-inch 1080p screen, a Snapdragon 800 processor, Sony's 20.1MP camera, and various other top-of-the-line hardware and software features. As you can probably tell from the video, the phone is currently running Android 4.4 (dig that transparent navigation bar). An announcement at Mobile World Congress later this month would make sense, but we haven't heard anything official yet.