I overwritten the file you said and it did nothing.
I shorten my filenames and it worked like a charm.
I have indeed quite a long filename syntax for my movies. I don't know how you figured it out but thanks a lot, the internet should be crowded with more people you!
/edit : In fact I was mistaken because I used a different folder with non-formatted (hence shorter) filenames. The problem was not the filenames' lenght but the special characters in the source foldername "D:\Mes documents\Mes vid
éos". If I change the 'é' to 'e' then it's ok