C:\Users\FMS>rustup component add rustc
info: component 'rustc' for target 'x86_64-pc-windows-msvc' is up to date
C:\Users\FMS>rustup default stable
info: using existing install for 'stable-x86_64-pc-windows-msvc'
info: default toolchain set to 'stable-x86_64-pc-windows-msvc'
stable-x86_64-pc-windows-msvc unchanged - (rustc does not exist)
Are you sure that your file is called main.rs and that it resides in a src subfolder next to your Cargo.toml?
Usually you would not create these files manually like shown in this video but call cargo new hello_world instead, which creates a hello_world/Cargo.toml and hello_world/src/main.rs for you. hello_world can of course be changed to whatever you like.