(TAS tutorial series) Re-recording -- what is it?

This video clip shows what it is like to perfect some scene in a TAS (tool-assisted speedrun) using re-recording.
The goal in this video is to walk through the stream of water without touching any of the jumping critters or the river bed. Normally, one would kill the wight on the ledge on the left, and push the rock to the hole where the critters come from, allowing to walk unbothered through the stream. But it's too much hassle in a TAS, when you can just walk through, dodging the critters. 🙂

Also, the critters were not the only problem: The stream is strong and if the characters get stuck anywhere for an instant (such as hit a wall), they will be pushed backwards, which constitutes a failure.

The first 3:41 minutes of this movie show the re-recording session to achieve the optimal path, and the last 30 seconds show what was actually achieved.

(In case you wonder why I walk and not run, it's because the stream is strong: the characters cannot run there. They're on the verge of getting pulled back on each step they take.)
Also, the emulator ran much slower when I played this. Parts were played at frame advance. The recording shows it at full speed. By estimate, about 10 minutes were spent here.

More information about the Chrono Cross TAS here: http://tasvideos.org/Bisqwit/Projects...