It can be very time-consuming trying to figure out specific character movements, often meaning that you have to playtest and tweak until you have it just right. I've had many frustrating moments where the characters have moved slightly too far, putting the rest of the "scene" out of sync. Or where the cut scene has frozen because characters are trying to move but are walking into walls.
With this utility, which can be downloaded here, it takes some of the pain away. What it does is allow you to record the keystrokes from the directional keys, then either preview it as a graphical representation or as a "live" demonstration (playing back the recorded keystrokes) in RMXP itself.
As you can see from the snapshot above, you can also save the current movement commands and load them later for additional tweaking and testing.
Since using this utility, the amount of time taken for cutscenes where a lot of character and NPC movement is required has been slashed in half. It's very useful to be able to test that out before actually implementing it in the Command Events and then having to go back in to edit them manually.
If you're like me and have a lot of movement in your games, then this utility will assuredly help. It's one of those rare gems you stumble across that certainly help you out and you don't want to get rid of - even after there are no further updates.