File Format

Header

Offset (+Hex)	Type	Name	Information
0000	dword	version	Version numbers: 0x2711 - New movies 0x2710 - Old movies
0004	dword	columns	The number of columns.
0008	dword	rows	The number of rows.
000C	dword	unknown1	Unknown value, it's 1 in the begining movies.

If the version is 0x2711 then this section comes right after the header.

Offset (+Hex)	Type	Name	Information
0000	dword	sounds	The number of sounds in the file.
0004	char[50 * sounds]	sound_files	A sound file name is 50 bytes long. It's an array with sounds giving the number of sound files there are.
*	dword[3200]	unknown	It undoubtedly has something to do with sounds. However, the only movie file that has values other than 0xFFFFFFFF in all the slots is dwarf_fortress.cmv so it's purpose is still unknown. I do know from testing that it specifies when sounds get played, but due to the finite number of slots I have not come up with a theory explaining how it relates.

The Sounds section & Header section comes before this. The remainder of the file is made up this way.

Offset (+Hex)	Type	Name	Information
0000	dword	size	The size of the following compressed data.
0004	byte[size]	sound_files	Zlib's deflate compressed data, comprising no more than 200 sequential frames.

Offset (+Hex)	Type	Name	Information
0000	char[Header.columns * Header.rows]	characters	The characters making up the frame.
*	attribute[Header.columns * Header.rows]	attributes	The color attributes of each character in the frame.

Iterate through the frame data:

 +---------> +Y
 |
 |
 |
 |
 V
+X

Or: Index = X * Header.rows + Y

A frame is a single byte long, the bits are layed out as:

0ibbbfff
i   - Foreground Intensity Bit
bbb - Background Color Bits
fff - Foreground Color Bits