you never run anything... this is why firefox doesnt have the option to run cus it maybe a virus. you save, scan for viruses then double click to install. although im a little confused as to why youd be downloading the worst browser in history anyway :S
can save and run it later. meaning can install it later after saving it to your HDD.
Run, it saves imediantly and it will open automaticly.
it is running the installer, not the program
You run it.