In my experience, you do not have to do all these clicky manuevers ;p You can of course if you want to, but, if you're lazy you can simply remove the guard option and they will begin to actually attack. What these other guys are doing, is what you almost would call exploitative game mechanics. Essentially they are maximizing their initial attack by getting as many spears into the enemy formation as possible. I wouldnt call it an exploit, rather imaginative use of the formation ;p

Guard Option for the Phalanx works unlike any other unit. They will not actively engage, they will simply hold their formation and engage anything that comes into their killing zone. About the only time I want them to use this, is when im massively outnumbered in a defensive action, or in siege defence. All other instances, make sure you turn guard off, or your phalanxes will march up and stop just short. Many of the previous posters have mentioned ways that you can force a phalanx in guard mode into attacking, but in my opinion its more trouble than its worth, and in my experience they contort all the faster as they try to regain a defensive position rather than an offensive one.