I'm familiar with LAMP systems and have been programming mostly in PHP for the past 4 years. I'm learning Python and playing around with Nginx a little bit.
We're working on a project website which will handle a lot of http handle requests, stream videos(mostly from a provider like youtube or vimeo). My colleague has experience with OpenBSD and has insisted that we use it as an alternative to linux.

The reason that we want to use OpenBSD is that it's well known for
it's security.
The reason we chose Python is that it's fast.
The reason we want to use Nginx is that it's known to be able to
handle more http request when compared to Apache.
The reason we want to use NoSQL is that MySQL is known to have
problems in scalability when the databases grows.

We want the web pages to load as fast as possible (caching and cdn's will be used) using the minimum amount of hardware possible. That's why we want to use ONPN (OpenBSD,Nginx,Python,Nosql) instead of the traditional LAMP (Linux,Apache,Mysql,PHP).
We're not a very big company so we're using opensource technologies. Any suggestion is appreciated on how to use these software as a platform and giving hardware suggestions is also appreciated. Any criticism is also welcomed.
My advice - if you don't know how to use these technologies - don't do it. Few servers will cost you less than the time spent mastering technologies you don't know. If you want to try them out - do it. One by one, not everything at once. There is no magic solution on how to use them.
How to utilize OpenBSD, Nginx, Python and NoSQL