hey i have been doing a weird but really cool move i somehow jump on the dragons head and slay the dragon with a thrust of my sword, question is how the heck am i doing this??? I dont think im pushing buttons differently and im on xbox360, so how the heck am i doing this very cool move??

It is a random kill animation. There is no way of doing it manually, it just happens when the enemy you're facing has low health.

As Legion said, it is a killing move.
This can happen to most, if not all creatures.

With different animations of course

Yep, it is and do you know, I've played hundreds of hours now and never once had it go into a kill animation for a dragon...I'm serious! I wonder if it's the angle you approach. Usually, I'm filling them with arrows and magic from afar, then sprinting in for the last couple shots in melee. But there's never a kill move. So odd, but it's no biggie to me.

There are different animations for different weapons. I jump up on the dragon's head and cleave it's skull with my battle-axe. Seriously epic finale.

It′s safer to attack from the side if melee, but the kill move seems to be triggered from the front

Yeah, I believe you have to be in a certain place. You certainly can't jump on a dragons head if you're slashing his behind.

Wait. Your name is Talos. And your rank is deviner. :/ ?

Are you who I think you are!?

It's a killcam. Savor the feeling of awe for now as the novelty will wear off very quickly.

Indeed! Haha. But ya, I am in front a lot of the time but probably off to the side. I tend not to take potions of elemental protection so I stay out of the way of dragon maws, maybe I'll quaff one and go head to head and see what happens. Maybe I'll fight one barehanded and see if they have a finishing move/kill cam for that. American Ninja Warrior style!

Of course, son.

Oh. There for a moment, I thought this was the first mention I've ever seen of what I do intentionally ever time I'm starting a new character in Helgen. It's right after the dragon attacks and you run into the first tower. You have to go up the stairs quickly with the intent in mind, as you have a short window to do it. But when Alduin busts his head into the window, you can totally hop on top of him. Onto his head. The first time I thought to try and did it, I was hoping against hope that if I stood still, I could ride until I was shook off up into the air. Never happens cause you get brushed by the walls in the tight space between tower and house.

Before I allowed the newer patches, I learned of the trick to leave Helgen and fast travel to Helgen still bound. You appear outside the walls, but can hop you way up to some of the real high up mountain rocks overlooking the town. I tried repeatedly to do the way more cool timed leap onto Alduin's back as he sweeps by since he flys close enough beneath some of the rocks, but never managed anything but a fall to my death. I came real close once.

I've done that kill animation to dragons before, and it is pretty sweet. But to me, my favorite was the time I got off a final shot archery killcam to take a dragon out that swooped low, coming for me to strafe me with fire and shot it dead out of the air. Say what you will about killcam animations, but I absolutely love the archery ones. To top it off, after it slow-moed the shot into the oncoming dragon, his dead body slid to a stop at my feet. I went to third person (a view I can't stand except for seeing changes in what you equip or wear) just to watch the soul absorb after that epic finale, to the dragonborn music.