By far the best solution I have found to this problem (I am german too) - preface the video link with 'ss'
Like this:
http://www.ssyoutube.com/watch?v=-UmL7xZZSUk
(remove the 'feature=player_embedded&' crap after copying the link to your url bar)
The great thing about this is: no extra software needed (though there is an extension and an bookmarklet) and it gives you links to all video resolutions.
Proxtube didn't work for me when I tried it and most of the time I like to download the videos with a download manager, which speeds things up on my slow connection (though the Flash Player seems to have gotten faster on my netbook, both download and playback-wise.