Where can I find good free quality VFX effects stock library? I'm having fun with HitFilm software and playing with my kids to make movies. I'd like to add some VFX to our creations. Where can I find a good bunch of stock video and audio effects? 

Usually our movies are Full HD resolution.
I've just found this nice Video &amp; Filmmaker Magazine list of free stuff.
Some of them:


Chroma Key Backgrounds 
Cute Stock Footage
LightLeakLove