Hello,
Running the most recent version of Premiere Pro CC 2014 (8.2.0) I also just purchased a brand new mac pro tower (3.5 GHz 6-core, 16GB Ram running Yosemite)
Before purchase of mac pro and update of Premiere Pro (old version was 8.1.0) my quicktime H264 exports looked fine. (settings at 18,000 kbps, 1280x720, max bit rate, keyframe every 12 frames)
Now, I'm getting blocky, low quality exports that are HALF the file size of my previous exports. What gives? This is not the first time I've had random quality loss on exports. Is this a bug with the latest update? Are there codecs I need to download to my new machine? I copied over the quicktime components from my old tower already.
Please don't suggest that I export with the mp4 wrapper, since Vimeo tends to have subtle sync issues with this wrapper. I prefer the .mov quicktime files. (Though a recent test with the mp4 wrapper looks equally as bad.)
Settings are attached in this screengrab.