Not familiar with "Smack It" so I can't really advise on that. Whatever works for you. With YouTube videos you gotta make sure that you keep the file size small - I think 100MB is the size limit for the entire file. It might be simpler to use a program like Bink to reduce the file size and just upload it like that if you don't feel confident using something like Windows Movie Maker to combine different files into a single video and/or attaching an opening title/ending credits.

You should probably go for something simple like what you did with the Darling Harbour video which seems to be just that one file uploaded on its own.