What software are you using? I find audio parts of sped-up videos pretty difficult, other than on the ipod line of products (even in quicktime).
There is some info here:
http://www.catonmat.net/blog/how-to-save-time-by-watching-videos-at-higher-playback-speeds/
I use VLC's playback speed (fine) options. Right now I'm taking a few recorded lecture classes and I can get them up to 1.4x without any difficulty in understanding or comprehension.
A place to discuss potentially promising methods of intelligence amplification in the broad sense of general methods, tools, diets, regimens, or substances that boost cognition (memory, creativity, focus, etc.): anything from SuperMemo to Piracetam to regular exercise to eating lots of animal fat to binaural beats, whether it works or not. Where's the highest expected value? What's easiest to make part of your daily routine? Hopefully discussion here will lead to concise top level posts describing what works for a more self-improvement-savvy Less Wrong.
Lists of potential interventions are great, but even better would be a thorough analysis of a single intervention: costs, benefits, ease, et cetera. This way the comment threads will be more structured and organized. Less Wrong is pretty confused about IA, so even if you're not an expert, a quick analysis or link to a metastudy about e.g. exercise could be very helpful.
Added: Adam Atlas is now hosting an IA wiki: BetterBrains! Bookmark it, add to it, make it awesome.