Hello Anton!
I have installed this plug-in and when started a SU , came a window:

Error Loading File C:/Users/Jenő/AppData/Roaming/SketchUp/SketchUp 2016/SketchUp/Plugins/MSPhysics/main.rb
Error: #<Exception: An exception occurred while loading MSPhysics library. The exception occurred due to one or more of the following reasons:

• Encoding::CompatibilityError: incompatible character encodings: Windows-1250 and UTF-8
• Encoding::CompatibilityError: incompatible character encodings: Windows-1250 and UTF-8

C:/Program Files/SketchUp/SketchUp 2016/Tools/extensions.rb:197:in require' C:/Program Files/SketchUp/SketchUp 2016/Tools/extensions.rb:197:in load'
C:/Users/Jenő/AppData/Roaming/SketchUp/SketchUp 2016/SketchUp/Plugins/MSPhysics.rb:90:in register_extension' C:/Users/Jenő/AppData/Roaming/SketchUp/SketchUp 2016/SketchUp/Plugins/MSPhysics.rb:90:in module:MSPhysics'
C:/Users/Jenő/AppData/Roaming/SketchUp/SketchUp 2016/SketchUp/Plugins/MSPhysics.rb:72:in `<top (required)>'
My SU is 2016 64 bit (16.1.2104)
My wsystem WIN10