"Google has rolled out a first update its mobile YouTube client for S60 devices which brings an improved support for touch user interface and the 5th edition of S60 platform.

Unfortunately application is still not fully optimized for the high resolution screens and fails to work in full screen mode and play videos on native resolution but at least it now supports on screen keyboards which means that you can now search through entirely YouTube catalogue.
...."

http://www.symbian-freak.com/downloads/freeware/cat_s60_5th/descriptions/internet/a_new_and_improved_youtube_for_s60_devices.htm