Discovered this great free VPN service called spotflux - it is so easy to use. On public networks, every website you visit can be tracked - VPN tunnels your traffic to spotflux servers. Though - the price you pay is having ads getting injected into unsecured html (http).
For example, there is a black rectangle. For me, it looks like this (with adblock enabled):
Inspecting the html code, it turns out this is just a div container:
I notice that this inserts a <div> with randomized id. In mine, it is id="azk91987". Since this <div> is top level, if you tried blocking it, you'd either block just that instance (with that id) or all <div>'s (which isn't what you want).
I noticed that the style is consistent though;
<div style="position: fixed; z-index: 9999; bottom: 0px; width: 100%;">
So I added a custom rule to adblock in chrome:
That's all folks.