I did spend 25 minutes watching this video at 2x and I think it was a poor decision compared to reading the slides in 5 or 10 minutes.
Also, it's a big hassle to download videos from youtube, because youtube doesn't want you to do it and plays cat and mouse games. I used youtube's own beta html5 player, which lets me do 2x playback (in mac/safari, but not in mac/chrome wtf). But youtube throttles download speed to normal playback speed, so I had to wait 25 minutes before watching. (Other ways of getting videos do not throttle speed, but back when I downloaded them as files, I usually couldn't get them fast.)
You're right, reading the slides is probably enough for this video but I guess there are some videos which you want to (or have to) watch but are too slow.
I myself use MySpeed. It costs 29$ but you don't have to download the video and can change the playback speed from 0.3 to 3.0. There are probably equivalent programs for free, but my google-fu wasn't strong enough to find them.
Not entirely relevant to the main issues of lesswrong, but possibly still of interest: my talk entitled "von Neumann probes and Dyson spheres: what exploratory engineering can tell us about the Fermi paradox".
Abstract: The Fermi paradox is the contrast between the high estimate of the likelihood of extraterritorial civilizations, and the lack of visible evidence of them. But what sort of evidence should we expect to see? This is what exploratory engineering can tell us, giving us estimates of what kind of cosmic structures are plausibly constructable by advanced civilizations, and what traces they would leave. Based on our current knowledge, it seems that it would be easy for such a civilization to rapidly occupy vast swathes of the universe in a visible fashion. There are game-theoretic reasons to suppose that they would do so. This leads to a worsening of the Fermi paradox, reducing the likelihood of "advanced but unseen" civilizations, even in other galaxies.
The slides from the talk can be found here (thanks, Luke!).