Still I'm think that alg+pgup is king of confusing, since people cannot learn about this shortcut unless they see the source code. 
Of course I can add a wiki page for this, but I don't think a _user_ viewing a page produced by pdf2htmlEX (by some other party) would go all the way to the wiki here.
So I'd suggest remove it. On the other hand, I checked pdf.js, they use jkl;np for navigating, might be worth a try if you are interested.