SUMMARY The interface offers the user a way to easily open the recording and open the containing folder, so having it one level deeper in ~/Videos would keep user home folders tidy and not impede discoverability of the location.
~/Videos/Screencasts/ is the default folder. Are you sure you're using default settings?
My spectaclerc shows: [VideoSave] translatedScreencastsFolder=Screencasts This puts them in ~/Screencasts. Is this maybe leftover from an old config. I doubt I would've ever chosen to put them in ~/Screencasts.
Nope, the old default was ~/Videos. I'm not sure how this could have happened.
translatedScreencastsFolder is a setting that keeps the original subfolder name, but doesn't directly set the save folder. It exists so that if you normally use one language, switch to another and take a screenshot/recording, you won't end up with two folders with different translations of "Screenshots" or "Screencasts".
I don't know how, but my Videos folder got unset. I must have deleted it or something. Sorry for the noise.