Apple's iChat had a wonderful feature called iChat Theater--also present in the Mountain Lion version of Messages, just without the "iChat" in its name--that let you share photos, PDFs, or Keynote presentations during a video chat. I used it countless times to give virtual presentations: An audience watching on a projection screen in a remote location could see video of me alongside my Keynote presentation, and I could see video of the audience plus a miniature view of my presentation (and anything else on my screen, such as my email or a Web browser).
But then Theater disappeared in the Mavericks version of Messages.
In a recent Mac 911 column, Chris Breen suggested a couple of workarounds. I'd like to share a few more, and add my own take on one of Chris's suggestions.
Back to Mountain Lion
Chris's first suggestion was also the first thing I tried to do when Theater disappeared: boot my Mac from a spare hard drive containing Mountain Lion and use the older version of Messages. That works pretty well, but I encountered a few gotchas that you might want to consider before taking that route.
First is the hassle of rebooting--even if I don't do it frequently, I still have to make sure that all the files, apps, and other resources I need are available from the spare drive.
Second, if the audience's Mac is running Mavericks, Theater still works, but instead of showing my video beside my presentation, it uses a picture-in-picture view (with a movable inset). So I must leave extra room for the inset picture on all my slides.
As an alternative to booting from an external drive, I tried running Mountain Lion in a virtual machine on my Mavericks Mac using VMware Fusion. Unfortunately, even after routing my camera to the virtual machine, Messages couldn't see it--neither my internal FaceTime camera nor an external USB webcam. I tried the same thing in Parallels Desktop, and although it appeared to work a bit better (Messages could access my camera, at least), I couldn't see the video of the audience or myself, and the audience couldn't see my Keynote presentation.
Which led me to consider third-party apps and services for videoconferencing, webinars, and virtual meetings of all sorts. After trying about a dozen of them, I've noticed some trends.
Almost all third-party video/screen-sharing solutions require either a downloaded app or a Flash-based browser interface (with its attendant performance and compatibility concerns). Some also require the audience to set up an account before viewing a presentation. With iChat or Messages, I could count on the fact that pretty much any Mac user would have the necessary hardware, software, and account setup. Not so with the third-party solutions.
Since no third-party app lets me run my live Keynote presentation in a window the way Theater did, the next best thing is to run my presentation normally (filling the screen) and share my screen with the audience. But that blocks my view of the audience (as well as anything else on my screen). Even with two monitors, Keynote either uses the second screen for the presenter display or blacks it out entirely.
Some people work around this problem by recording a movie of a Keynote presentation and then playing it back in its own window, but that makes it difficult to time transitions properly and almost impossible to adapt the presentation on the fly--by, say, jumping to slides out of order. Saving the presentation as a PDF means losing all transitions, builds, actions, audio, and video. And although you could give someone else access to your Keynote presentation so they can run it themselves alongside a video chat, you wouldn't be able to control the timing.
Microsoft PowerPoint has an option to run a presentation in a separate window (choose Slide Show > Set Up Show, click Browsed By an Individual (Window), and click OK), which can also be used (if expanded to full screen) to fill one screen while leaving the other free for other apps. Although I prefer Keynote, PowerPoint isn't a terrible compromise for remote presentations.
Meanwhile, I want to be sure the audience sees video of me and my presentation at the same time. Lots of services display only a presentation on the audience screen, along with audio of the presenter. But for me, live video is mandatory. Some services that offer both video and screen-sharing make you choose one or the other--that is, turning on screen-sharing turns off the presenter's camera.
Options worth considering
I also found that many of the services are aimed squarely at big businesses, with prices to match. But there are numerous options that cost less than $25 per month and offer both two-way video and screen-sharing. Chris mentioned Zoom (which I also found to be a reasonable option) and the paid version of GoToMeeting (which, at $49 per month, is too pricey for me).
Of the numerous other services I've tried, here are my top contenders at the moment:
Skype Microsoft's Skype is free for basic use, but with a Premium account, you also get screen-sharing and other features. Skype isn't quite universal, but it's pretty close--and only the presenter needs the Premium account. (A Premium account costs $10 per month, but if you plan to use it only occasionally, you can get a $5 day pass as needed; there's also a one-week free trial available.) I can show video of myself and a shared screen or window simultaneously. As long as I'm willing to use PowerPoint instead of Keynote (so I can run the presentation in a separate window, or on a separate screen), it's reasonably close in functionality to Messages Theater.
Fuze MeetingFuze Meeting from FuzeBox also lets me share any display or application, and uses a free app for both host and audience. When I activate screen-sharing, Fuze initially shares the full desktop of my main display while hiding its own interface, so it takes a few non-obvious clicks to share an arbitrary application while still seeing my audience.
If I upload a PowerPoint presentation, I can play it right in the app, without having to share my screen. Fuze also supports uploading presentations from Keynote '09 (but not Keynote 6), although it converts Keynote files to movies before displaying them, which isn't great. Fuze is free for up to 25 participants; plans that support larger meetings start at $8 per month.
Google+ Hangouts By itself, the free Google+ Hangouts can't do simultaneous video and screen-sharing from the same computer. I've worked around this by using two Macs, joining the same hangout (with the same account) on each one, using one for video while the other displays my presentation. That's a clunky workaround, but it gets the job done--and it works with Keynote.
A more elegant solution is to use the free edition of Telestream's Wirecast for YouTube, which lets you create all sorts of views within Google+ Hangouts--including side-by-side and picture-in-picture, with video of yourself and a window or monitor (for example, with a PowerPoint presentation) shown simultaneously. But, fair warning: Wirecast is not the most self-explanatory app. Expect to spend some time reading the manual and experimenting before you achieve the effects you want.