I found Youtube and Google video very useful for finding all kinds of reference videos.
The availability of video cameras and the free space to publicly show videos results in a fantastic library. People are filming anything they can see, from simply people walking on the street or their own pets to acting out scenes, and most bizarre things.
Here are some I used as reference for different movements and situations in my project:
for the strangling bit
for the swimming
swimming in a river 1
swimming in a river 2