Some in-development footage of Skate 4 in action leaked onto a video site yesterday, and EA acted swiftly to remove it. However — the internet being what it is — the clip has been passed around quite a bit since the leak, and you can still find it on YouTube if you put in the magic words. (Hint: the magic words are "Skate 4.")
To be perfectly honest, the clip isn't anything special: in it, a skater rides down a hill, pulls some sick grinds, and then front-flips directly into the ground. The city environment that surrounds the skater is obviously unfinished, with very little detail on the buildings and streets that he passes. As someone who isn't particularly well-versed in the Skate series, if you had told me that this was a clip from one of the many Skate-inspired indie games on Steam, I probably would've believed you.
