Open source webcasting?

SPARC is looking for some open source webcasting software to replace the proprietary software they are currently using, Infinite Conferencing. The crucial functionality they need is:
(1) Slide delivery – They need to be able to conduct a powerpoint/slideshow presentation over the web in a user-friendly manner, without having to download any plugins. I am unclear on how Infinite does this, Jennifer suggested that it might be ActiveX, but that would only work on Windows/IE and she also claims to have used it on a Mac, so that can’t be right.
(2) Text chat – IRC + web portals should be good enough to handle this?
If we could do those two things in an open source fashion, they could just a conference call on a phone line to handle the audio portion, and ditch the proprietary software. Of course, it would be nice to handle that and other things online as well, so other useful features would include:
* Group VOIP chat / online conference calls
* Video option
* reliable
* easy to install + use.

Any ideas folks? C’mon lazyweb, I’m counting on you 😉

Free stock footage is hard to find

I am trying to make a video using free stock footage from the internet. It is very difficult! For some reason I thought it would be easy, because I frequently use free stock photographs from e.g. Flickr when putting together presentations, and I have no trouble finding high-quality, Creative Commons-licensed photos. Video is clearly different, unfortunately.

Here are my requirements/preferences for stock footage:
(1) Downloadable in high resolution/quality – This is problematic, because most video on the internet is in low-resolution Flash formats. Even when it is possible to download the flash file (which frequently takes some hacking), the video is too low-resolution to use for serious video-editing. Ideally I would like the video to have a resolution of 640×480 or higher.
(2) Freely licensed – Ideally I would like to use public domain or CC-licensed footage, with a license that permits me to make derivative works. This basically reduces my options to the Internet Archive and a few video-sharing sites such as Revver, most of the stuff on YouTube and its ilk is not freely-licensed.
(3) Actually relevant to the topic I am covering – It is actually rather difficult to find footage illustrating a particular concept/idea… the current state of video search is pathetic.

Does anyone have any ideas for websites / sources that meet these criteria?

I’ve had some success with the Internet Archive, but it has been a long and painful process, and I wish I could find some other options as well.

My trials and tribulations with the Internet Archive.