the point of 3b1b's video wasn't "how can I figure out what words are still an option", but "what is the optimal word to guess at each step to minimize overall

the point of 3b1b's video wasn't "how can I figure out what words are still an option", but "what is the optimal word to guess at each step to minimize overall attempts needed to solve". Picking a "good" word will give you more information about the actual solution than picking a bad word, so you will get there faster.