I agree. The problem is that modern slide design says that slides shouldn't be done in a way that lets them work independently of the presentation. That is, slides are there to provide structure and illustrate things that are difficult to describe verbally, but aren't meant to repeat what the presenter is saying.

It would be very nice if these online slide presentations came with the speaker's notes that actually cover the main points of what they're saying (with explanation). This assumes that these notes exist, but I feel that the slides by themselves are not very valuable.

(No disrespect meant to Armin Ronacher — I use his work every day and I'm a big fan of what he's done for the Python community.)