Wait... So this guy was handing out free access to a FTP server to test your HTML5 apps? Doesn't he realize the dangers of that? Like, couldn't some random person go into that server, and just delete all those test pages? Or perhaps worse, hack the site and put some dirty stuff up in there? But I suppose you pretty much trust the people in this community. Or unless there is some restriction that prevents you from doing certain things on the FTP server.. But I suppose reading the P.S. note below, you were already pretty aware of that.
Also, as a casual, you can at least play around with the games/apps that are uploaded there.