Thank you Genete, Donal and Rafael 
Genete, I’m sorry, I don’t know why, but now I can’t reproduce the error …
Maybe yesterday, I had too many open files, and my computer is not powerful enough?
I accelerated the crow.
I had one criticism of a french forum, they say that all is not consistent. It is true that I have done all in pieces, it may not be a good idea finally ?
I tried to desaturate a bit the rendered video so that the colors blend better …
https://docs.google.com/leaf?id=0BzP3O3afEG04N2I0YTlkYTMtODRjZC00ODU1LWIwMDMtYzM0MGRlMzExYzMx&sort=name&layout=list&num=50
Hi MadO, I ‘m very interested in learning more about animated backgrounds and I really enjoyed following your work on ‘Wind on grass’ and was very impressed with the final result. During the thread you mentioned to DarthFurby that “This is really a mask effect: the grass is a “noise gradient” + “noise displace”. I duplicate it, and add a rotation to the top canvas.
This rotated canvas appears in regions with a high feather (“onto”) and the regions are animated.
I can give you more explanations if you want.”
I would be so interested and grateful to hear any more ‘explanations’ that you might like to share about this, as I’m very inspired by your work. Thanks and the best of luck with your future projects.
Hello Donal, and thank you for your comments
I’ll try to do a tutorial.
genete, should I do it on the wiki? my English is not good …
[edit] I can write in French, try to make a translation in English, and maybe you (or Rafael?) could correct the text?
Yeah, wiki is for that. Please add it to Advanced Tutorials.
Your English is infinitely better than my French 
In any case it would be better that the original were made in English. If you doubt on something, just make citation in French or use the talk page to clarify the English version. Sure that you’ll explain it very well. 
-G
MadO, your words are like music to my ears, I look forward to this very much and I agree with Genete that your English is good enough to do this. Much of what is written on the forum here and on the wiki has been written by people who do not have English as their first language but it is almost always possible to understand what they mean. Now I think that I will go and watch ‘Wind on grass’ again, just to wet my appetite.
Of course, any problem. Tell me when it’s done.