As you probably noticed, video quality of presentations vary greatly. I'm always amazed by the quality of the PyCon recordings: http://pycon.tv I'm speaking as an user; I don't have any affiliation with the PyCon AV team, nor I know anything about recording video.
I understand that you want to run the conference as non-proft, but I'm willing to pay to have good quality videos for this conference since I won't be able to attend, and I assume other people will be willing to pay as well. Maybe you could setup a donation page to raise money to record the videos.
I'm one part of http://www.44con.com/ and having run quite a few events in London would be happy to help out where I can. It might be worth at least meeting up for a chat to see what you want to do and bounce a few ideas around. My contact details are on my profile if you'd care to get in touch (as you don't have any on yours and a search for dotemacs on google yields quite a few results!).
I've worked on it before, so you can PM me if you have any questions.
- stable, straight facing video
- clear mic sound with decent loudness
ps: since competent people are proposing help, I might be redundant.