Shane, the issue is that Apple opted not to support these codecs in AVF and by extension the QT Player app. They did for DV, but not the others. So it really has nothing to do with the fact that these are 32-bit. Merely that Apple opted to limit the amount of work required on their part. While inconvenient, and in some cases hard to justify, you have to draw the line somewhere, I suppose.
This mainly affects these codecs if they are wrapped in an .mov wrapper. Apple left it up to others to write the necessary modules. This is what Avid, BMD, and Adobe have done for DNx wrapped as .mxf. Depending on the codec in macOS, QT will ignore some and convert (transcode) others. Get a professional player tool if needed, like Switch. Don’t rely on QT.
– Oliver
Oliver Peters – oliverpeters.com