Here are Kraistus’ instructions:
1. Use the phone’s native(!) WEB-browser, and go to: m.google.com (For example Opera Mobile won’t work, you won’t have the change to select Youtube)
2. You have to choose a language which is supported in the app(!). Choose for example: English(US)
3. Choose the Youtube icon to download the app to your phone
4. Install and enjoy!
I have not tried this yet but Kraistus says it’s better image quality than previous mobile web youtube (though still needs improvement).
Thanks also to Ashkay who also emailed us a link to blog-n8.fr who also had some screenshots.