Google's YouTube team thankfully seem to work at a fair old pace. In this case following up a new client (S60) with several updates to fix bugs. The latest is v2.0.11 and fixes a major bug where videos played at high speed on some devices. You can get the (excellent and free) YouTube client for any S60 3rd Edition phone by going to m.google.com in Web.

 (And no, this doesn't work properly with the 5800 yet...)