Hi David,
Man I have the very same problem.
I was looking for the same answer in Google and ended up in this thread. Have you managed to work that out? Doing some more search on Google I have found this – I will test it now, hope that works.
https://philipbloom.net/2013/08/25/premiereluts/
Last paragraph:
“Now to retain a little more film grain on your grade: Usually when using film grain for online (web) version delivery, it looks pretty good on the rendered h.264 version but that film grain will get lost on the next generation H.264 re-encoding loss on Vimeo or Youtube and your footage will look very poor. Even pushing the H.264 encoder unto 25Mbps does little to hold the grain. But unlike say using the Apple ProRes 422 (HQ) master transcode at 184 Mbps (at 25p) the 38 Mbps Apple ProRes 422 (Proxy) data rate is much more suitable for an online delivery format and Youtube & Vimeo can still manage to digest it. Of course 38Mbps still adds up fast, but if you need film grain to hold then this is the way to go.”
Hope that works or that you worked that out already.
Ricardo Lisboa