In watching this series, there is 1 major thing that I can gleam. Vulture harassment is extremely strong and forces protoss to sit back, but can be extremely easy to overdo. He can get massive damage with 2 or 3 vultures as protoss mass expands, wanting to contain terran and not having enough money to cannon up every base to avoid losing probes.

However, he would continue to try and push harassment. Even if he got damage, he would end up losing so many vultures that protoss attack would just kill him since he can be 12 or more vultures down.

A good lesson to take away from this, is only do harassment with 2-3 vultures really, and you have to actually get good damage (6-8 probes or more) to be worth the commitment when going for an expansion or you wont be able to hold your expo on many positions and mine out. This move is likely worth if you are in little risk on mining out though, and if protoss is camping at their base to defend from vultures then you can move across the map or expand much easier.