The most compatible cross platform video playback delivery system is Flash. I have also had great success lately doing live video streaming using Silverlight. The complaints I used to get from the Mac folks have gone away.
As far as REAL is concerned, I don't care if it can produce pristine HD over a dial-up connection, they are one of the most sneaky and unethical companies on the Internet.
Thanks to a couple of hearing-impaired people at Google, YouTube is working on Captioning, which really is great, but Flash is still AFAIK the most Caption Un-Friendly web/streaming video format. A quote about YouTube from Neowin "...just around 100,000 captioned videos available out of hundreds of millions of clips posted on the site." [http://www.neowin.net/news/main/09/11/19/youtube-captions-to-use-technology-from-google-voice]
I personally think it somewhat ironic that web video folk worry about cross-platform playability, whilst in effect flipping off hundreds of millions of potential viewers! For comparison, Apple is projected to sell 33 mill. MACs 2006 - 2010 [http://macdailynews.com/index.php/weblog/comments/computer_industry_almanac_apple_projected_to_sell_33_million_macs/]. True, current MAC users may complain, but greasing the squeaky wheel in this case means ignoring much, Much larger audience that's so used to being dissed we hardly ever b**** anymore... I mean, why bother -- we'll just spend our $ elsewhere.
>"Just to add to the venting about Real...
>I've scrupulously avoided having anything to do with them..."
You have every right to be ticked off, & you should be... I've got reasons to dis-like Real -- along with probably a couple dozen other companies. But there's a cliche you often hear in the movies: something to the effect that "it's nothing personal -- just business". Very often it really is just biz as usual, & whether you stay pi**** or not has really no effect on how any CEO enjoys their morning coffee. By all means vote with your wallet, & do what you will to keep whatever cash from reaching their bank deposits, but at the end of the day I think it helps to be pragmatic & not let whatever company cost you, whether it's future opportunities or sleep.
I just read the posts about the Real sitiuation. I thought the restore option was a wise move if you can do it. Microsoft has some software tools you might be interested in using. (free) http://onecare.live.com/site/en-us/default.htm