I'm waiting for the encoder support.
I want to see how much disk space can be saved with this for archival purposes.
Well there are encoders out there, both x265 and VP9 are open source, however it will likely take a looong while yet until they have been improved to reach the actual potential of their respective specifications. Currently they are also very slow, much slower than they need to be due to lack of optimization. However if you want to try them out now (like I'm doing) you can simply build them from source: