Deadliest Warrior was indeed removed from Netflix.

However it is still available to rent, not as a download but the actual DVD for $7.99/month (if you are a costumer residing in America)
This happened because Netflix only keeps films on their available to watch online list, if they are on demand. In other words only films that are popular by being requested to be streamed on a regular basis by a lot of people will remain on Netflix homepage.
If you would like to see which films are available to stream at the moment on Netflix, follow the link below where you will find that list.
-For the United Kingdom
http://netflixukcompletelist.blogspot.com/
-For the United States of America:
http://netflixusacompletelist.blogspot.com/
Also, gradually more shows are available online these days, sometimes even the full episode is available to stream. I'm sure if you have the time and patience to look for it, you will find it.
