Most 24-bit displays are actually 32-bit, since 3 byte alignment is the devil's work. When an 24-bit image is loaded for display purposes it is often converted to a 32-bit representation in which one byte (normally used for alpha channel) is ignored.
Packed pixel modes, where 3 bytes are used to represent a pixel on screen are generally the preserve of old display cards.
Of course they are, I know that, but he was talking about 24 bits, not 32
