Need help to understand which skills are at stake in those websites

Hi,
I'm not myself a technical person. Hence my little knowledge in software/web development and this thread. But I think this is definitely the right place. I really liked all the information I can find here and look forward to exploring more. I've been thrilled to see how people were easily helping each other. I have a question, I would really appreciate if any of you can help. Here it is - which technical skills are required to build something like "ehow" website: http://www.ehow.com ?
I mean you can upload videos, add content, embed them into other websites, download the apps on your phone or tablet, comment, and so forth. What tech guy can build that: software engineers? web developers/engineers? API developers? They both have pretty much the same skills (like a software engineer is able to lauch such a website with all the "background" we don't see to make it works)?

Thank you very much for your help,

I look forward to hearing from you.