How to encode from Premiere using nvenc Nvidia codec but still output to mp4/avi
It's funny how you can try solutions for hours but the moment you post a question online or to IRC you find the answer yourself within minutes.. Anyways, digging around I found tat instead of using mp4box as my multiplexer I changed to TsMux as per the thread instructions and that still didnt' work however I noticed I had one more option, mkvmerge, so I tracked that down here: http://www.videohelp.com/software/MKVtoolnix , installed it and used that instead and viola, it did the trick.  Was able to use the nvenc codec and get a video in the end that was accepted by youtube.  

Now of course because I have solved this problem it would appear that the nvenc codec is no longer using my gpu at all after upgrading to the latest nvidia drivers so there's that issue to solve but at least I can use the codec and get useable vids.  Hopefully this is useful to someone else experiencing the same issue down the road