Intel movtoy4m!
Tyler Loch has sent me a patch that makes movto4ym run natively on the Intel architecture! Turns out that only two lines needed changes, and not ten times that, as I had feared. For the curious, k32ARGBPixelFormat was changed to k32BGRAPixelFormat. Thanks QuickTime, and thanks Tyler! Download the latest version of movtoy4m on this web site.