It works!
It takes some time to load the file, due to size I guess, It freezes ands starts again, but ... it works
This method also is fine for making screenshots in general (i tested from dvds f.e) and I would call it much better, as we can make screenshots at exactly the time point we want, while with rutorrent screenshots are taken automatically, and we can't set exactly the time we want.
Perhaps the other one is easier, but this one has better results.
Anyway, we have 2 ways to choose and this is great!
Thank you once more.