We have seen a lot of leaks of Windows Phone 8.1 mostly in the form of Screenshots or the leaks from developer SDK which was text. So far we have not seen any video of WP8.1 in action and here we have it for the first time on Nokia Lumia 520.

The most interesting thing here is that you can see WP8.1 running on Lumia 520 will 3 columns of tiles (medium tiles) but the previous leaks suggested that the 3 columns of tiles would only come to phones with screen-size of 4.5″ inch and more and thus this can be assumed to be one of the beta builds of Windows Phone 8.1.

You can also find the build to be buggy & slow but here it is.