Hi,
I was running into this same error before (while running glview too, not just ofxKinect). It appears to be coming from isochronous transfer frame scheduling problems (see
http://libusb.6.n5.nabble.com/BUG-Darwin-isochronous-transfers-td396026.html; this post also includes a way to get more informative debugging messages from libusb on OS X), and gets worse during heavy CPU loading.
If you adjust the number in the line that begins with "frame +=" (should be line 1213) in libusb/libusb/os/darwin_usb.c in the libusb library, you can slightly improve the amount of time that the camera feed lasts before dying. (For testing robustness, I can usually force the camera stream(s) to die by calling up Expose a lot, because that always lags my poor old computer.) Unfortunately, in my experience, tweaking this value can only improve the situation so far, is frustratingly inelegant— and the streams still eventually die.
The best solution that I've found so far (which is hacky and may make those actually familiar with USB driver programming smack their foreheads), is to edit src/usb_libusb10.c in libfreenect to restart isochronous transfers that die. After editing, it should read:
FN_WARNING("Isochronous transfer error: %d\n", xfer->status);
libusb_submit_transfer(xfer);
//strm->dead_xfers++;
You'll still get error messages (unless you comment out the warning line, I suppose), and the framerate may be affected, but the streams will at least stop freezing up.
Hope this helps. I'd be curious to figure out why only some people are having this problem on OS X, and how to fix it properly once and for all.
Best,
Cameron