First question, the video - I don't know about that at the moment, but I'm pretty sure we'll release a trailer later on if we get more things done,
Secondly, well, the class information is really "classified", but I'll give you some ideas -
1. Priests... well... anyone should know about them heal, buff, blablabla, but these guys are "untouchable"
2. Archers, they're far ranged shooters as well as melee in OoL,
3. Swordsmans mainly lead up on combos and chances for a particular skill.
Thirdly, You will not have a limit to the amount of spells you can use at one time, but there WILL be cooldowns of spells to make things more fair.
Fourthly, to Soulja, well, that's just AoDC's test thing, it's nothing like that.