Instance, formerly named Itsdagram, is considered to be one of the better Instagram knockoffs available for Windows Phone users and will be adding support for uploading videos soon. But for now, WPGram will offer Windows Phone users the ability to view videos and pictures, add 'likes' and post comments. The only thing it doesn't do is upload your pictures or videos.
The app will cost you all of 99 cents and is compatible with Windows Phone 7.5 and Windows Phone 8 flavored models.
source: WPGram via WMPoweruser