This is a High-Level Analyzer (HLA) Extension for Saleae Logic.
It provides a set of protocol decoders for the MultiWii Serial Protocol. This operates at 115200n1 and is used for configurator control (typically over USB, but can also be over serial) and for other functions such as HD OSD, VTX etc.
See MSP-Extensions and DisplayPort for Betaflight specific extensions to this protocol.
Implementation of MSP support in Betaflight may be found at:
https://github.com/betaflight/betaflight/tree/master/src/main/msp
This is a work in progress and is continuing to be developed.