That clip is taken straight after the character was given his class, at that point he had not visited a single miracle, but was still retribute most of the melee attacks, even later he still had not gotten the retribute (counter attack) skill:
He is not supposed to be able to attack after blocking by default .. right?
That's an odd one. Not seen that before. If it happens again, could you send the abbeycore.txt in the game folder (typically C:\Program Files (x86)\Steam\steamapps\common\Godhood ) to email@example.com for them to have a look at? Should help in seeing what's being called on there. (The log clears itself each time you start the game, so would need to be done after it occurs, preferably sooner after than later)