This just relates to the whole presentation thing and not the relation to JGO, but I wanted to share my opinions on the presentation.
It's very hard for one to realize that they cannot go straight into making games once they pick up a language. These people who are looking at Minecraft will probably think of Java to program with if they realize it is programmed in that language. I started off with Java, partially because I thought Minecraft was awesome and partially because I wanted to fix the bugs you had mentioned in a blog post that Catacomb Snatch needed fixing (this is back in 2011 or something). So I set it up and immediately I was very confused. I started a game way too early, and the result was
Hunger Games Board Game, which does not really use object-orientation at all. So a very good point will definitely be to advise people not to jump into games too quickly. Baby steps are critical.
You could mention that if they get discouraged with Java, that a more simple language may be better to start. Some people are likely not prepared for the syntax of Java when they have never dealt with anything prior, so maybe Python or Ruby may be better for a start at times. Even while only being a freshman in high school, I have helped somebody learn programming, and even though they were interested in it for the scientific simulation possibilities rather than the game creation possibilities, I started them with Python. I did this because I had a friend before who would give up as soon as they reached any bug. It is
way easier to create a bug in programming than in scripting (though all of that is debatable). I think that people who want to jump right into games will likely get discouraged squashing bugs. Maybe hinting at the possibility of simpler languages for the start would be good. Then, you can get into game development quicker than with a more-programming language like Java.
It's also nice to think of a
color spectrum with programming vs. scripting. You give one end to programming and one end to scripting. Assembly/machine code goes to the programming end, and something like Python or simpler would go on the scripting end. From there, many languages are between, and how much time you have and what you want to do determines where on the spectrum your language will be.