Which one should I download?

Standalone application: Use this if you use video editing software that doesn't support the plugins offered, you want a drop-in replacement for ntscQT, or you really need fine-grained control over interlacing.

If you're using Kdenlive, Blender, the free version of Hitfilm, Final Cut, or any web-based video editing software, you'll need to use the standalone application.
OpenFX plugin: Use this if your video editing software supports OpenFX plugins.

OpenFX-compatible editing software includes DaVinci Resolve, MAGIX Vegas (nee Sony Vegas), Hitfilm Pro, Nuke, and possibly the paid version of Filmora.
After Effects/Premiere plugin: What it says on the tin. Use this if you edit using the Adobe suite.

System requirements

If you don't have a computer that runs Windows, macOS, or Linux (for instance, a mobile device or a Chromebook), try the web app.

Added the new "2D" and "2D Adaptive" chroma demodulation filter options. These are mainly useful if you want to avoid more prominent NTSC artifacts.
Removed the "Scanline phase shift" and "Scanline phase shift offset" options, since only one value is really correct for NTSC anyway.
Fixed a bug where the preset manager would fail to load the first time the application is used.
Re-enabled multithreading, which had been accidentally disabled.
Reduced the size of the standalone application bundle by removing unnecessary GStreamer plugins.

For installation instructions and further guidance, see the Getting Started guide on the ntsc-rs website.