it's tough to understand the clumsy part, there isn't really anything that tells us this part. The flirting bit is a bit unclear but I do sense the show-off aspect of it. Let's look at the technique, but I can elaborate on the acting a bit.
In it's current state, he looks down, then up, and goes right into his more proud stance. What's missing is the thought process inside that character so we understand each beat. What would help for instance is a moment where he kinda snaps out of his sad trance, after around x184, where he would blink and look a bit left and right (mostly with his eyes, not moving his whole body) and then realizes that the camera is on him. You want to see that realization in his face BEFORE he moves into the poses on x198 and 219, which show him being more of a show off.
I'm not sure if that hip move from x262 to 282 is very successful. It's not very clear in terms of acting ideas, whereas the last weight shift after x283 fits more the "victoria's secret" intention you mentioned. Although it's still a bit weird in terms of character change, where he goes from a more masculine type from x218 to around x245, with the belly out and rubbing it, to a more feminine weight shift and model pose at the end. So character wise he feels a bit unfocused when you have him go through so many different emotions and characters, from sad, to excited, to proud, to show-off-y to sexy.
Animation wise, I would avoid moments of twinning, where both arms are moving at the same time with the same posing, like on x186 to 204 (at least the end posing of the arms is a bit offset, but overall they start moving at the same time and both arms seem to go through the same key rhythm).
Make sure that when one part of the body moves that it affects the rest of the body. So after x219, where the arm goes forward and the hand rubs the belly, that arm movement feels very disconnected. You'd have to involve more of the shoulder and a bit of the chest.
The steps and weight shift from x246 to x269 need a bit more work regarding balance. The foot starts to move after x246, so the weight will go from both legs supporting the body to one leg, since one leg is in the air (or should be, otherwise you have him ice skate around). So around x251, the screen left foot should be a bit off the ground and the body leaned over screen right, so that the screen right leg is supporting the weight. If the character has any hip controls, then you'd have to bring up the screen right hip as well, showing the weight distribution.
Around x259 the body should move screen left (right now it's off balance to the right) since the screen right leg is moving. All the weight is on the screen left leg and the body needs to keep the balance working.
When you do the weight shift from x283 to around x294, the body doesn't move side to side, where the weight is over one leg and then over the other. Right now it looks like the body pivots from the middle and from there the chest and hip rotate to change the pose, which feels too static. The body has to translate over for the correct weight shift as well.
Let me know if you more questions!