Hulu and Amazon stream using flash only, over largely reverse-engineerable protocols. See, for example, the XBMC plugins for those services which work quite well. Now neither Hulu nor Amazon have the depth of content availability that Netflix does, but they're clearly not shackled by DRM handcuffs either.

I don't know about that. I've tried reversing Hulu's player to access their *.flv files, but they appear to do some sort of handshake that is uniquely generated for each user session and hashed.

It may not be easy, but it's been done. Check out the source to the bluecop Hulu plugin for XBMC if you're curious. All the content goes over conventional streams. There's no deeply-integrated "DRM" layer, just stuff you can do from flash.