Flashstreamworks has a post by Jens Loeffler breaking down the why and the what behind OSMF. Here’s a taste:
So why do you need a framework?
decision depends on your use case. If are building a small website, with
some static videos, the existing components might work well and provide
a great default UI. A different case are more advanced video projects.
The players might simply not fulfill your requirements, therefore you
have to build a wrapper on top of it, or even build your own framework
from ground up – if you ever built your own video framework, you
probably know this can be a pretty intensive task, and certainly
something you don’t to do for each individual video project.
Read more over at Flashstreamworks…