What's the right setup for recording programming talks?
I do this all the time for local user groups and I'm yet to find a "plug and play/set and forget" solution. To do the recordings at a professional quality, you need some sort of skill and training, otherwise it will look amateur. 

If all you want to record is the person talking, and not what's on their screen, it's relatively easy: buy a wireless lapel mic (the Samson Airline range is good) and plug it into a video camera of your choice that has audio input. Put that on a tripod and away you go. Then copy that on to a computer, trim the top and tail in something like iMovie, then export to YouTube or whatever format you like.

If you want to do multiple microphones for discussions, then you need to buy more than one mic (a couple of Sennheiser MD46 mics are great for this - one per person) and plug them into a mixer (Behringer mixers are fine and cost effective), then plug a recording device (such as a Zoom H4N) or the camera into the mixer's outputs (using the tape output, 2x RCA to 3.5mm for example).

When it gets tricky is if you want to record the presenter's slides/demos as well as them talking, in videos like so: https://vimeo.com/omtconf/videos/page:1/sort:alphabetical

That requires more than $1,000, plus a bit of A/V knowledge that's probably too long winded for this response. You also need to do some editing in post. It can be done live (using something like a Blackmagic ATEM switcher), but will cost even more and you'd need a bit more training than two minutes. Upside however, if being able to easily live stream it to the web, using that sort of setup, so people who can't make it can watch. 

If you've got any specific questions, feel free to ask for more info :)