Preferably into an flv file (which I also know that is the source of the streaming video in the cases that I mean)
I was told that the protection that I am facing is probably an encrypted Java applet inside an HTML page.
downloadhelper.net is the best video downloader which I ever encountered but it fails in this case.
I informed its developers but nothing has been done so far, and I informed them months ago.
The site which causes me the trouble is in their support list.
VLC player also fails @ it as far as I managed.
Another trick which combines wireshark (but not its packages download feature) to get 2 URLs and a browser which was published in a youtube film fails too, and that trick even failed on youtube films on which it was exampled by the time of its creation.
Everything fails and no one helped me so far at it.
Will anyone here take the challenge?

If downloading their streams is against the ToS then I will close this thread.

If this is against their TOS then it is illegal and cannot or should not be done. Youtube I just use youtube2mp3, but that just creates an audio file for me to use on my ipod. I'm not even sure if it is legit.

My question is not about how to download videos from youtube.
Almost every downloader does it.
When refering to youtube, I just referred to one trick taught in youtube, which fails @ it as well as in the site in which I do encounter problems @ it.
It is worth mentioning that I once had the video which I want to download, but my hard disk got destroyed and I did not have it backed up.
My problem is in downloading from a website which is not youtube, and I explained it in my opening post.

Yes, we know. But you never said which website. So there's no way to guess what the issue is.