The other audio effect in Windows Movie Maker is mute. This is really just if you want to have the video without the associated audio. This may be useful for montages, music videos, and other abstract moments where the visuals are important out of context. You may just want to mute out a specific part, which will then require you to cut that part out of the clip specifically, keep it in its original order, and then mute it. You may then want to Fade Out on the clip before it and then Fade In on the one after. Just as with the Fades, you may want to have secondary audio at all times when using a mute.