I am using Windows 10 Pro and Audacity 3.0.2. I have downloaded the ffmpeg-win-2.2.2 zip file, extracted it and gone through the preferences>libraries>locate procedure, but it doesn’t recognise that I have done that and will not let me inport an mp4 file. I have also downloaded and run the exe version, no idea where that places the files, don’t seem to sow up on Windows search.
Note that Audacity for Windows is now available as 32-bit or 64-bit.
If you use 64-bit windows, the 64-bit version of Audacity is recommended (default).
If you use the 64-bit version of Audacity, you must also use the 64-bit version of Fmpeg (and any VST plug-ins must also be 64-bit versions).