I cover seminars and conferences based either on a flat daily fee, guaranteed sales or direct sales. Direct sales is, essentially, a "speculation" approach and I rarely offer this one unless attendance is estimated at 1,000 or more.
The most popular is more or less a "work for hire" but not really, in that the organizing group guarantees to purchase, say 300 copies, and I shoot, edit, produce and deliver them at a cost-per-DVD. That cost is based on numbers for me, with 100 or less at $25 each; 100-200 at $20; down to $10-$12 for 500 or more.
I have occasionally charged a flat daily fee based on my standard $100 per hour rate — $1,000 for 10 hours or less, then hold a six-week "sales" period where I obtain a list of attendees, and/or the organizing group provides advance, at event and post event promotion of the DVDs being available by a professional video producer. This is popular because I can offer the DVDs at up to $15 or so, either FOB or drop off all orders to a central location or, if the company insists, work out some direct-mail fulfillment with them providing the mailing labels and a check-list.
Going in as a newbie it is easy to shaft yourself because you cannot know all the potential things that can crop up on you. Even with experience I have to say that the unexpected ALWAYS happens and rarely is production, delivery and sales of such programs a "piece of cake."
So, while you aren't necessarily "experienced" with all facets of this production and sales approach, don't be tempted to accept the company's description of how easy and/or straight-forward it all will be. Require choice of placement, use of lights and auxiliary audio, and pick your battles without caving in to every perceived threat from them. They want it cheap, fast and good. Now days that is possible, but don't make the "cheap" I like to say affordable, so low that you come out frazzled and penniless.