I am giving up now. I cannot upload big files to http://www.yousendit.com/ . Either my internet connection is not stable enough (ADSL 2mbit) or yousendit has a problem or both. I have tried several times to upload 250MB chuncks of the "Durch die Nacht" video without success.

I think, http upload is not a very sophisticated and efficient way. They also offer https upload, which I do not think is better. I will try again next week, when I am back.