I've heard that some of the newer prontos have something called hex ?? or something?? Basically, I was wondering if there is a way to choose a specific input on a tv (like video 4 for example) when the tv's remote only has a "tv/video" button or "input" as a way to choose a specific input.

Yes there definately is a possibility there may be discrete codes for each input as well as on/off. However that is dependant on the Brand and model TV you are talking about. Go to the files section/discrete codes and then look up your Brand TV.
If it's in there more than likely it will work. As far as hex codes goes..yes thats what the IR codes are refered to and new and old both use them.

That's right, each brand should have specific discreet codes which you will probably find here. These are very necessary files when you are running macros and such since many remotes have single button you must toggle through for various commands such as video 1, 2, 3, etc, and on/off.

Not every brand has discrete codes. There are a lot of makes and models that do not have them. But you will find a lot here in the files section.