I totally understand the way you load the buttons and LOVE the idea. In Europe some people were quite concerned that social media sites track all their movements because if you visit a website that loads these share/like buttons the traditional way while you're logged in i.e. with FB, FB knows you've visited that site so this method is awesome for people concerned about their privacy but the flickering is bad.
As I see, the moment I hover, you hide the icons, load the scripts and replace the icon with the script.
Could it be possible to load the scripts the moment one hovers but only hide the images when the script has finished loading? That would do away with the flickering?