Henry or Harry?

So, I was totally about to put up a post complaining that King Henry is the most boring man who ever lived, and I saw that pretty much everyone else was having the same problem. I decided that for me, if I'm watching a movie, even if the beginning is hard to follow, I can actually sit through the whole thing and pay attention. And basically, once I gave it a chance "HENRY V" (1989) was the coolest! It totally got me interested in what was going on. I recognized Christian Bale as a little boy, and IMDB'd it. Plus, Kenneth Branaugh gives some seriously chilling speeches:

This one's right in the beginning:

And this one is the most famous of the play:

I noticed in the movie that they kept calling king Henry by Harry - I suppose it is a nickname - and I did some research, and found out that Falstaff refers to him as 'Hal' in 'King Henry IV.' This change in his name may be on purpose, to demonstrate the change that takes place in Harry between the two plays. Henry V grows into his own, and begins to speak and act like a king, rather than the youth he was in the other play. 

Here's a link to a searchable online version of Henry IV:
http://www.online-literature.com/shakespeare/henryIV1/