It is a cute video, and he looks like a sweetheart. Nice attitude and a pleasant way of going.
As for dressage, he's got some things working against him. First of all, he's built like a racehorse (duh! He's a TB, right?) By that, I mean he's built to go hollow or inverted, and he has very little muscling on his top line - going on the aids or rounding up is going to be really hard for him. Second, he has a fairly long back, so again, rounding up is going to be hard. Third, he moves very close behind, which means he doesn't have a good base of support for some movements.
That doesn't mean you *shouldn't* do dressage with him, just that you should be aware of those characteristics and limitations and that he's not going to be an international dressage superstar. Some lower level work will muscle his top line and probably improve the quality of his movement and it might add some interest to your flat work.
I'd also recommend you work with a dressage coach to get you started. Working in dressage with TBs has some special challenges and it's really helpful to have someone on the ground observing. I'd also want to make very sure you didn't do anything to spoil his good nature and lovely attitude.