Visualizing algorithms is unfair, because some people were born without vision and therefore cannot "visualize".
That, and--though it wouldn't have helped in this case--the most I heard about epilepsy complaints is on forums with flashy animated GIF images. Why do they browse with GIF animation enabled? Really, if it's such a health hazard, and images posted on a forum can give you dangerous seizures, why would you take a risk and trust on the goodwill of the community and take your chances with the occasional troll?
I don't want to dismiss the problem, not at all, I just wonder about the victim mentality displayed and lack of proactiveness.
Especially the display filter. If it's an actual health hazard, you shouldn't be asking people not to show flashing imagery on their sites, you should be taking action yourself, making sure your computer display is unable to display this imagery. Any kind of modern 3D GFX card should easily be able to detect flashing areas and dampen and/or motion blur them so they're safe, without much processing power needed. You'll be erring on the side of caution of course, so some video content might be degraded (though with a well-designed filter this should be minimal) so you'll want a key-combo to (at your own risk) temporarily disable the filter (with a parental lock for the children, of course).
It seems to me that the most likely explanation is that the risk is so minimal that people with epilepsy aren't even willing to give up lolcat gifs for it, though it is possible that people are unable to conceive of a setting existing to disable a largely unnecessary feature in a piece of software.
If it is a significant danger, and people don't realize you can disable it, then that seems to indicate a significant failing of the entire system, from doctors to parents to people taking care of themselves properly. I really want to believe that it isn't the case.
The visualization of maze generation in the presentation is pretty neat, and is meant to demonstrate the running algorithm. The author isn't making it inaccessible on purpose, he can't possibly know about all the accessibility guidelines, and even if he does, there is content which can't meet all the guidelines.