$16 for a *very* non-performant material? If this was intended for use in high-detail scenes, not meant for gameplay, one would generally just use a flipbook animation, or looping HD video texture (both of which are higher quality and available for free all over). I love options, but c'mon, that's pretty steep. $5, maybe. And you can loop in materials, using custom HLSL nodes. Also, there are better ways of doing this, all around. Somewhere on the forums, Ryan Brucks (of Epic fame) himself touched on this. I've personally been working on a cool water material (not "material blueprint", thankyouverymuch) and utility functions, and am close to the quality achieved here, sitting at ~180 instructions with everything "turned on". The kicker? It's pure procedural. No textures are needed. So this is cool, no doubt about that. In my humble opinion though, it's not "good". It doesn't run fast, and it's more complicated than it needs to be.
Lee is right - you can use a gradient effect when you vertex paint in your chosen 3d modelling platform (I've done it in max), meaning the wind effect shifts from nothing to maximum along the length of the leaf/branch/whatever.
NoEmotion HDRs might be the best place to look for HDRs. It is basically a treasury of free HDRs, which you can use for both personal and commercial work. The developers spent 350 hours to create 150 HDRs. Images were taken over a period of roughly 10 months.
The collection includes day, evening and night scenarios. Most of the pictures are said to be taken around Prague and Czech Republic. A few mountain shots are from Swiss Alps. You can use these HDRs with any render engines.
Each image is 300MB and there is a bandwith limit of roughly 1TB per day, so please don’t download everything at once. You can find the breakdown of the creation process and other details on the collection here.