Topic is misleading. It might be true on .Net as the Version is 3.0.3, which might be the latest released Version for .Net (there is a prerelease of 4.8) but compared to Java it is ancient.
Dino Esposito describes an "historical" crud System in a series in msdn magazine https://msdn.microsoft.com/magazine/mt703431
This is basically ES with crud. Not saying ES with crud is the best example, but for data which requires Audit Trail logic it actually works fairly well.
Let's look at some real live x265 benchmarks, because you skipped the part where they did it on a beefy dual socket server.
Let's take: http://x265.ru/en/x265-hd-benchmark, that benchmark is 1080P, let's assume you're correct with your simplicity and it might be closer to reality.
The fastest listed system there does a blazing 33fps (well that's a broadwell, the 2015 dual socket server is probably atleast the xeon equivalent of it).
And we haven't even looked at the image quality/compression artifacts.
I disagree with your assessment.
Rivvr is apparently a spinoff of Sixa, the appropriate techcrunch article https://techcrunch.com/2016/12/09/sixa-secures-3-5m-as-it-la... repeats the 11ms latency. Maybe it's the same technology? The comments to the techchrunch article do not sound convincing either.
I wonder how that should work. Less than 11ms per Frame compression time, let's say 9ms (as we need to Account for the way back too for latency) for a 2160 x 1200 stream + audio. And you can't see any compression and we're talking Close up here. Not possible with h264/h265.