Right click -> View source -> Ctrl+A (select all) -> Ctrl+C (Copy to clipboard) -> Open your preferred text editor (mine is Notepad++) -> Ctrl+V (Paste from clipboard) -> Replace ">" with ">\r" -> enjoy the source reading.

Takes max 10 seconds, on any site. Can you do it in less than 10 seconds using that validator?

That would give you new lines, but not indentation..

But my point was that the markup is invalid.