Need Tips on Improving my Smash [Video]

pretty good! too fast to see any errors...

nothing much to add... perhaps if there was slow mo, we can see if there's any area for improvement

 

Hmmmm, the right leg thing mentioned by cheung might be a balance issue.
Of course, it doesn't mean you're supposed to be perfectly vertical when executing the smash....
In fact, when you use your back muscles and the chain of muscles going up to the shoulders, to transfer the energy, you'll tend to lean into your non-dominant hand (as that's where the follow-through should end up).

To improve the balance (if it is the issue) I'd recommend doing a lot of core strengthening. Even if it's not a problem, having greater core strength and stability will improve everything over all (not just your smash).
In general, I'm a big believer in balance. If you can maintain good balance, you won't waste energy in the jump as well as the landing (and then the split step into forward lunging); this will help with your jump smashes as well. I noticed some of the landings were slightly off balance (granted even pros can miss their landings sometimes and blotch their smash altogether); this will help your recovery after smashing.

Lastly, you mentioned you played 1.5 hrs before this smash compilation... Depending on your competitiveness, you should work on your stamina. Keep in mind that most tournaments are 6 hrs (well the ones I've played in) and sometimes you'll have back-to-back games (if you have bad luck/draws). If your form gets sloppy after just 1.5 hrs of playing, you will be very prone to injury playing in these types of tournaments because you will try to push your muscles even when they are at exhaustion.
A part of being an athlete (competitive or recreational) is training so that you don't put yourself in situations where you'll injury yourself. Imagine injuring yourself on court and affecting your off-court life.
If you play only 1.5 hrs each session at the recreational level, then train to be able to handle that and don't go beyond that too often. And if you play 3+ hrs, also train accordingly.

 

I can't comment on what I can't see. From this far, the swing looks fine to me. No comment on the jump.

I am more curious of your string and tension. You keep adjusting your string after each smash, and the sound! kinda awkward.

 

if you're trying to copy a dog peeing, then you're doing a good job.
I'd be worried if I was your doubles partner, if I stand beside you, you might kick me mid-smash.

 

You should not work on playing an hour straight single matches to improve stamina. Generally one loses consistency and quality of shots. If you have time to work on an hour straight full of matches, you could be using that time for game simulations and practicing consistency and quality of shots! I suppose that may be if you plan to play at a higher level.

In terms of playing an hour and a half straight, do you eat inbetween games? I highly recommend it as if you think about it, playing for that long without eating will do work to hurt your body in terms of lack of nutrients.

If you talk about injuries, make sure to stretch before and after matches! Static stretching is definitely good after matches. If you are serious about reducing stretches, search dynamic stretch for before matches.

EDIT:

The last shot before the video ends, for a start you do not look like you get behind the shuttle. You also look like you have almost a forward swing before you backswing for your clear.

 

LMFAO haah made my day that :')