I wanted to explain a power of using new Unity Video Recorder feature with VR Panorama. Video recorder still isn’t included into a unity, but it can be downloaded from Github:
https://github.com/Unity-Technologies/GenericRecorder-FrameCapturerPlugin

Once downloaded, it will give you a new menu item under Tools/Recorder/Video. When you open this menu, you will get a new window where you can set various setting. For this tutorial, let’s say that we want to record 360 stereo SBS video in 4K.
-set Selected recorder to UTJ/MP4 (this says that you want to use mp4 output format)
-Set source to GameDisplay (this means that you want to render a screen output and not any specific camera – VR Panorama will automatically be loaded as only camera)
-Set resolution to X2160p_4k (this instructs Recorder to use vertical resolution of 2160pixels
-Set Aspect Ratio to X16_9 (this value will be calculated automatically by Unity – and it will default to standard 4K value from VR Panorama)
All other fields are relative to your project.

Now let’s set VR Panorama to render correctly:
Add a VR Capture component to your camera (as you would normaly).
-Set VR Panorama Capture Mode to VR Panorama RT (this means that VR Panorama will render only to screen without using it’s own video management).
-Set Capture type to Equidistant stereo (or any other mode that you want; Note that Video mode doesn’t work in RT Mode)
-From VR Panorama presets, choose 4K preset (you have to match this preset with Unity Video recorder resolution).
-Set other options that you would set normaly in VR capture. like speed vs. quality and so on.

Now you can render directly to a video file. this new approach will give you some speed improvements as there is no need to save intermediary files and recompress them. And this unity solution is native.
I will be working on integrating it in a tight manner, so you can expect that in future this workflow can be made easy, and that all parameters gets synced automatically.