If I were British, I'd vote no on the Alternative Vote

I was always skeptical about it. It was rather difficult to find out just what was being proposed. This video does was the first clear explanation how it works (which is confirmed by the BBC, though the video oversimplifies things by having all the Greens put the Lib-Dems as their first choice, etc.), including the anomalous results that it can produce. Even if the possibility of actually hurting a candidate by putting them first is overstated, the system is still too complicated and has an element of unpredictability in it.

Here's what I mean: plurality voting, called First Past the Post in the UK, is like a two dimensional colored block puzzle where you try to make blocks disappear by pushing them around on a flat plane lining them up three or more at a time to make them vanish without being left with just one or two of any color. The Alternative vote would be a three dimensional version of that game where if you make blocks disappear on the bottom it can set off a chain reaction as higher blocks fall into the empty spaces forming rows of their own and disappearing leading to more blocks falling. That is difficult to predict. But in this case it's impossible for anyone to predict because the higher blocks represent other people's votes and are protected by ballot secrecy.