[Patrick Melnyk]"I purchased an istockphoto.com video file in .mov format and when I brought it into AE it does not show the transparency (alpha). The preview clearly shows an obvious white and black area where the transparency should be but it won't display the video properly in AE."
That file does not actually contain an alpha channel per se. It has fill and matte, stored sequentially as RGB, not RGBA.
In other words, the second half of the movie is a luma matte [link] for the first half.
[Patrick Melnyk]"How can I get AE to recognize and display the transparency."
Import the footage. Split the layer (Ctrl-Shift-D on PC, Cmd-Shift-D on Mac) when the black and white part begins. Move the black and white footage directly above the color footage, then enable "Luma Matte" for the color footage.
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