Is this all coded manually?

Its not as hard as you think. For a start off the source code of that website contains loads and loads of white-space, if you took all of it out you would probably have more like 500 lines. Apart from that most content on a website you view will be generated using php and a database. For example all of the "featured videos" will be taken out of a database and put on to the page using about 7 lines of code, not 80 ...

So yeah, it will still be a fair bit of coding, but no where near 4600 lines worth, a good programmer would be able to knock up the homepage of that website in a matter of days/weeks.

No. Most serious web sites are NOT written using html. They are written in a scripting language like php with a mysql or similar database to carry information that might change regularly. php then reads back the data and builds the html according to the user visiting, or according to a particular request for information. All the sites I run are written this way, I write NO html as such, the index page just includes php files with the scripts, and apparently different pages sometimes include a different page, or the same page making different use of the data. Some of those scripts run to more lines than that. ALL manually coded in text editors.

No, they have to do it all by hand. I mean as far as I know. Maybe Bill Gates or someone could make some type of loop to do this. It would be extremely complicated to do it though.