The Mahalo guides are pretty useless. Anyone could pass the levels. It's just passing without losing a life that's important for the achievements. As mentioned above, the creeps also move differently even if you follow videos on youtube. There's a guide for Y Me? (possibly the hardest medium level) on youtube that has a perfect, but the creeps never ever moved down the middle when I followed it. Ended up I had to build several greens to "cup" two "Ys" to force them to go down the middle. Over 10 attempts, with trial and error eventually helping me to get through it perfectly.
Google "David Such" and you may find some image guides for some medium levels. Most of them work, but some aren't perfects as well, and it's incomplete. But still, more helpful than Mahalo videos that's for sure.