General structure:
<virtualDirs>
	<movieMatch name="Your directory name" description="Short directory description">
		... movie matching elements
	</movieMatch>
</virtualDirs>

Elements:

<virtualDirs>
Root element.

<movieMatch name="..." description="...">
Each movieMatch creates a new custom movie virtual directory. The name attribute defines the name in the Movies menu. The description attribute defines the text description of the custom movie virtual directory. (Currently don't support custom icons). Both name and description are required. All children of this element define matching characteristics for movies to appear in this custom movie virtual directory.

<title [type="i"]>...</title>
Match on movie title. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<title>Die Hard*</title>
This matches movies with title starting with Die Hard.

<plot [type="i"]>...</plot>
Match on movie plot. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<plot>*must save the world*</plot>
This matches movies with a plot that contains the text "...must save the world...".

<genre [type="i"]>...</genre>
Match on movie genre. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<genre>Action</genre>
This matches movies tagged with the Action genre.

<cast [type="i"]>...</cast>
Match on movie cast member name. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<cast>Bruce Willis</cast>
This matches movies with Bruce Willis as a cast member.

<director [type="i"]>...</director>
Match on movie director. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<director>Ron Howard</director>
This matches movies directed by Ron Howard.

<mpaaRating [type="i"]>...</mpaaRating>
Match on movie MPAA rating. Wildcards {*,?} may be used. Value must be text (e.g. PG, PG-13, R, etc.). The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<mpaaRating>R</mpaaRating>
This matches movies rated R by the MPAA.

<subtitles [type="i"]>...</subtitles>
Match on movie subtitles language. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<subtitles>Spanish</subtitles>
This matches movies that have Spanish subtitles.

<videoDescription [type="i"]>...</videoDescription>
Match on movie video description. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<videoDescription>MPEG-2*</videoDescription>
This matches movies MPEG-2 (DVDs) in any format/resolution. Note, common values for this field are like: "MPEG-2, NTSC, 720x480 (16:9)" or "DivX 5 (Perian, 448 x352, Millions", etc. (depends on container type: DVD, .mkv, ...).

<audioDescription [type="i"]>...</audioDescription>
Match on movie audio description. Wildcards {*,?} may be used. Value must be text. The type attribute is optional and if specified with value i, makes the match a case insensitive match. Example:
	<audioDescription>English</audioDescription>
This matches movies with an English audio track. Note, common values for this field are like: "English", "Spanish", or "MPEG Layer3, Stereo, 44.100 kHz", etc. (depends on container type: DVD, .mkv, ...).

<duration>...</duration>
Match on movie duration greater than or equal to the value. Value specified in minutes and must be numeric (can be floats). Example:
	<duration>90</duration>
This matches movies that are at least 90 minutes long.

<imdbUserRating>...</imdbUserRating>
Match on movie IMDB user rating greater than or equal to the value. Value specified on scale of 1-10 and must be numeric (can be floats). Example:
	<imdbUserRating>5.4</imdbUserRating>
This matches movies that have an IMDB user rating of at least 5.4/10.

<imdbTop250>...</imdbTop250>
Match on movie IMDB Top 250 ranking less than or equal to the value. Value specified on scale of 1-250 and must be numeric (integer). Example:
	<imdbTop250>33</imdbTop250>
This matches movies that have an IMDB Top 250 ranking of 33 or less.

<releaseDate>...</releaseDate>
Match on movie release date greater than or equal to the value. Value must be a common string representation of a date (e.g. 10/15/2007). Example:
	<releaseDate>10/15/2007</releaseDate>
This matches movies that have a release date greater than or equal to October 15, 2007.

<watched>...</watched>
Match on movie being watched or not. Value must be either 1 (watched) or 0 (not watched). Example:
	<watched>0</watched>
This matches movies that have not been watched.

<wonOscars>...</wonOscars>
Match on movie having won at least 1 Oscar or no Oscars. Value must be either 1 (has won at least 1 Oscar) or 0 (not won any Oscars). Example:
	<wonOscars>1</wonOscars>
This matches movies that have won at least 1 Oscar.

<not>...</not>
Negates the matching criteria of the child element. Value must be a single child element. Example:
	<not>
		<cast>Bruce Willis</cast>
	</not>
This matches movies that do not have Bruce Wills as a cast member.

<any>...</any>
Serves as a way to specify that movies can match on any criteria specified by child elements. Nesting of any movie matching elements is supported (including <any> and <all> elements). Example:
	<any>
		<title>Die Hard</title>
		<title>Die Hard 2</title>
	</any>
This will match both Die Hard and Die Hard 2.

<all>...</all>
Serves as a way to specify that movies must match on all criteria specified by child elements. Nesting of any movie matching elements is supported (including <any> and <all> elements). Example:
	<all>
		<title>Die Hard*</title>
		<cast>Bruce Willis</cast>
	</all>
This will match all movies with titles that start with Die Hard and have Bruce Willis.
As a side note, the <movieMatch> element behaves as an <all> element insofar as when child elements are added directly to it.