I recorded this a few days ago using a Google+ Hangout On Air as a screen capture application and an alternative to Slideshare slidecasts. For a straight PowerPoint presentation, I prefer making a slidecast (pre-record the audio, upload and sync), but if you have a multimodal presentation (i.e. more than PowerPoint - live web demos, etc, such as this) or multiple presenters, Hangouts are far superior. I think what this proves is the devastating effect PowerPoint has had on suffocating the life out of live presentations, from conferences to lectures. Faced with a decent tool like Hangouts we can't think what to do this it. The other value to hangouts is creating a sense of occasion around a live event (even if that's only student Office Hours) as opposed to the passive experience of watching a recording.
You can now make comments here, on the original Google+ thread or on the YouTube page. This could be problematic, but I could turn any of these comment streams off as needed. At the time, I had an audience of one (hopefully there'll be a few more listening in Tallinn). Many more people will watch the video subsequently - it'll be interesting to watch the YouTube Insights to see how many. More than go the the conference, I'm sure.
I still think hangouts are the potential killer app for Google+, I just haven't figured out how to use their full potential yet.