Make help & error message more clear.

[PegasisForever]

• There should be spaces between arguments, not equal sign.
• Tell user to install v4l2loopback in the error message.

[ShayBox]

That error message shouldn't be showing if v4l2 loop back isn't installed and loaded, it's checking for the virtual camera first

[PegasisForever]

It will show, see #15, he didn't have v4l2loopback installed.