Search for .bip or .bvh files. All Vizard avatars as well as many models on sites like Turbosquid use the 3Ds Max Biped, for which these animation files are (mostly) interchangeable. You can export the biped animations to the .CAF format Vizard uses with 3Ds Max.
http://motcap.com/ is a nice site that has lots of free motion-capture based animations.
https://www.mixamo.com/ has animations that you can tweak and preview on your own models, but most of them aren't free.
Protip: visit the websites of Motion Capture studios or system manufacturers. Many offer free sample data to show off how good their system is. You might find something useful in there
