I might pass on MH3 though, even though I enjoy the first, it just doesn't look like anything has changed. It still looks like a bog standard Monster-Stabbing-Till-It-Dies simulator. if they actually had things like leveling in it, maybe I would get it though. Thats my only problem with MH1, the lack of statistic improvement from my mass murderous ways.
A standard rpg style leveling system would be use-less in mh, increasing stats and gaining skills is already done by making better equipment and adding xp levels would remove the ability to go into a battle with a chefs knife and hunters armor just for a challenge.
Though the game will always be a Monster-Stabbing-Till-It-Dies(or is captured) simulator, there have been plenty of changes since the first game, just from the video you may have noticed the under water segments and if you were watching really closely, some of the weapons have new attacks and combos. Other then that, there are several new weapons types(Gun Lance, Tachi, Hunting Horn and Bow and arrows), armor skill values(in stead of just getting skills from have a specific set of armor) as well as gems that can add to armor skill values(giving you skills you may not be able to get other wise), guild trial quests(you chose from a set of equipment to complete special mission, that work a bit differently from normal ones), Monster pvp(capture monsters can be used to battle against another players captured monster) and probably some other crap i can't remember.
think this went on a little longer then i originally expected... in short, i'd say give the game another chance(try out the newest psp version or something maybe), there might not be anything mind blowing, but if you haven't played since mh1 there might be enough new stuff to get you into the game again.