I think ultimately, people want both overlaid and separate. We're working to
improve the system each year, but have been focused on consistency and quality,
which is challenging enough. There is probably also a way to take the PDFs and
overlay them on the video, if anyone wants to volunteer :)
Hopefully people have links to source files in the PDFs. That could also be
added to the video metadata, if, again, anyone wants to help. Our small and
oversubscribed conference team won't be able to do these things this year. We
do keep track of the ideas for the future, and we did make some slide gathering
improvements this year.