Ok, after some delay for re-tweaking the encoding settings for higher quality when needed, and pulling in some other improvements to the config system, all related updates to TimedMediaHandler have been merged. :D
If all goes well with the general deployments in the next few days, expect the beginning of VP9 rollout starting next week.
Changes since the earlier announcement:
* the new row-multithreading will be available, which allows higher threading usage at all resolutions; encoding times will be more like 1.5-2x slower instead of 3-4x slower.
* switch to constrained quality with a larger max bitrate: many files will become significantly smaller in their VP9 versions, but some will actually increase in exchange for a huge increase in quality -- this is mostly 60fps high-rate files, and those with lots of motion and detail that didn't compress well at the default low data rates.
-- brion