Some things you should know:
This site is based on these transcripts shared by u/veryseveralbeers and also includes many transcripts of NL's YouTube-only non-Isaac videos. I'll try to add new transcripts semi-regularly.
The search is very dumb (i.e. it will not autocorrect you, it will search exactly what you typed), and if there are more than 100 matches, only 100 of them will be displayed, the rest will be ignored, so be as specific as you can. For example, hello is bad because they say it often, and onii-chan or ram ranch are good because it's a very specific phrase they don't say often.
A few (clickable) search examples:
straight edge most
well that's what makes it worth doing
I call that Priscilla
what is WDW
notices your bulge
Azmodan got you
kidding I wouldn't hurt a fly