First off, I hope y’all pull off some way of archiving the talks. I’m out in CNY where electronic music creators/thinkers/nerds are very hard to come by. There is a real need for more stuff like this!!!
As for a solution, there is one very quick and dirty solution: do a simple (smartphone would work) video recording and then make the slides (either links to Prezis or other cloud-based slideshows OR pdfs of the PowerPoints) available with the video.
Beyond that, I think that a really elegant solution would be to use a webcam/screencap combination through OBS or some other streaming software. It can require a little computing horsepower, and you’ll need everyone to bring their presentations/videos on USB drives (or provide a Dropbox) but it avoids the issue of all having to reassemble multiple sources before uploading.
I’m sure there are more elegant solutions, but I can’t think of any at the moment. Curious to see what others come up with.