Thanks to the hard work of The Engineer, the site seems to be back, and the videos functional.
The problem was something to do with the embed code. A parameter changed, or was missing, that caused the video to stall upon loading, appearing as a black screen with a buffering symbol that never finishes loading. I’ve tried to go through all of the videos and double-check them myself, but there are about 600 posts on this blog. If you run across a video that does not work, e-mail me at firstname.lastname@example.org and I’ll fix it ASAP.