You can add items to the main meny by editing Home.xml in your skin directory (on my box it's located at /usr/local/share/xbmc/addons/skin.confluence/720p/Home.xml)
But the custom menu entries have to point somewhere. There are three video libraries in XBMC: Movies, TV-Shows and Music videos. This means you have to add your videos to one of these libraries unless you only only need to access them in "file mode" (without scraping ). If you want to separate, say, animated movies from your Movies library, there are two options that I am aware of:
1) Browse as files:
Don't add the animated movies to the Movies library. Add the animations directory as a source, but don't scan it. Add a menu entry that opens the animated movies directory in the video library "file mode", e.g.:
Code:
<item id="12">
<label>Animated Movies</label>
<onclick>ActivateWindow(10025,"/video/Movies-Animations/",return)</onclick>
<icon>special://skin/backgrounds/movies.jpg</icon>
<thumb>$INFO[Skin.String(Home_Custom_Back_Movies_Folder)]</thumb>
</item>
2) Use smart playlists:
Add your animated movies to the Movies library (just like you add all other movies). Create a smart playlist which contains all movies
except the animated ones, and one list that contains only animated movies. See how:
http://wiki.xbmc.org/index.php?title=Smart_Playlist
Then edit the "Movies" entry on the main menu to open the non-animations smart playlist instead of simply launching the Movies library. Also add a new entry which opens the animated movies playlist.
Code:
<onclick>ActivateWindow(10025,special://profile/playlists/video/Animated-movies.xsp,return)</onclick>