Hi FionordeQuester.
Creating a TAS is a completely different task opposed to creating an encode of a TAS, so this tutorial will most likely not cover the encoding steps. If you want to create a high quality encode of a TAS, have a look at
the encoding guide instead.
If you just need a quick encode, you can use "AVI/WAV -> record AVI" in FCEUX with a codec of your choice. A good choice for this is h264 with quality factor 20 (for example from "ffdshow-tryouts"). You can also test quality factor 0 (almost lossless) to see if the file size stays small enough for your needs. FCEUX and all other emulators I know of will use WAV for the audio part (about 10MB per minute!), so you might like to reencode the audio afterwards. As said, the encoding guide will explain this in much more detail. (My personal recommendation: don't use Windows Movie Maker, at least not for video games. AVIsynth is quite easy to use, and allows much more complex tasks.)