One enhancement which stood out was "Party Watch," whereby you can have your gaming party watch a Netflix on-demand movie, each at the same time. This resonates nicely with three other improvements: streaming movie playback under low-bandwidth conditions, improved party reconnects, and streamlined party invites. For my proposed purpose, it also resonates nicely with "avatar props."
A little-publicized feature of the Xbox 360 is that you can plug in a USB keyboard (including a wireless keyboard) and use it whenever the dashboard pop-up comes up for entering text.
So, you could have your "party watch" group make fun of the movie together, a la Mystery Science Theatre 3000 or Cinematic Titanic. Maybe the text pop-up is compressed and appears below the film. Maybe you can make a setting that causes the text line to be simply one line without the on-screen keyboard, since obviously you can see what you're typing by looking at your physical keyboard. Maybe you get to see everyone's avatars along the side or bottom of the screen, just like Mystery Science Theatre 3000 itself.
If they really want to get fancy, perhaps a future OS update could allow you to save the transcript of your party watch chat: with the text of each comment would be the gamer tag of the person who made it, a unique identifier for the movie, and the number of seconds into the movie that comment was made. Then, since anyone could play back the commentary along with the movie (a la Rifftrax) they could have little competitions on Xbox Live for the most humorous commentary, perhaps starting with older films which have passed out of copyright.
Anyway, that's the idea.
Any time you give people a chance to be creative and social at the same time, they tend to jump at the opportunity. Furthermore, this would be an entirely new way for Netflix to market its service: no matter where you are on the planet, watching a movie no longer needs to be a solitary, or passive, activity.