I would like to share a Youtube channel I run with my boyfriend that has slow motion reference footage for animators. It's called "SloMo Ref," it's free to use and filmed entirely by us at 240 fps. It's mainly footage of various animals, from rats to bears to fish, plus the occassional video of effects reference, such as snow being pushed off an object or waves on a beach.
The actual channel can be found here: https://www.youtube.com/channel/UCcfQVMHFyx1Ziy1ks6pCRZQ
We've also got Facebook and Tumblr pages for anyone who'd rather follow updates through those services.
Hopefully you can find something useful from the channel! Feel free to let us know if there's any particular animal or effects reference you'd like to see from us, we might just be able to help.