Liz from the YouTube team created a thread at YouTube Help explaining that YouTube has pulled the Realtime toolbar feature. Here is Liz's apology for removing it, on behalf of all of YouTube and Google:
We've seen some of you wondering what occurred to the Realtime Toolbar. The Realtime Toolbar was recently retired and is no longer an available feature on YouTube.
We were excited to release and experiment with Realtime and it has inspired us for new features on YouTube in the future. We look forward to introducing many new features in the coming months and are sharing them with you all. Many thanks to those of you who used Realtime and for your feedback to us on this feature- your suggestions and input help the Team shape the site and determine what should be developed to further improve the YouTube community.
If you forgot what the realtime toolbar did, you can still read about it at youtube.com/t/realtime_about, that is until that page is pulled. When the page is pulled, I have captured a screen shot of it and posted it on Flickr for all to see. But here is one piece of the toolbar:
It seems like not that many people were upset with the departure of the YouTube Realtime Toolbar.
Forum discussion at YouTube Help.