This is the only feedback I disagree with so far. I do not see how you can say that I have a bad toss
You say the problem isn't in your toss? There are several probable locations for your inability to get your weight properly into the ball.
1) Your upper body motion isn't good. That's hardly likely because any healthy person can swing a racket upwards without falling off to the side.
2) The lower body motion isn't good. There's hardly any to begin with. How could it possibly be your legs when you aren't even using them?
3) Your toss isn't where it should be, and your body is compensating by chasing it, resulting in your body weight going backwards prior to contact as opposed to forwards.
Look at your first video alone. I don't care if they're warmup serves. Anyone hitting warm up serves should easily be able to maintain their balance. You fall over on the first 3 serves, hit 1 or 2 reasonable ones, then hit one where you stumble COMPLETELY out of the frame. Whether you try to argue that it was just a warmup or an actual serve, YOU'RE WAY OFF BALANCE HITTING THE BALL. Were you serving in 30 mph winds? If not, then WHY are you falling off to the side? This needs to be addressed before you think about landing further into the court.
Right leg swings out to the right because he's falling to his left, and needs the counterbalance to stay on his feet.
^
Look at the first video alone and look at the difference in the depth of your toss. The ones where you get the ball 1-2 feet into the court results in a relatively balanced finish.
Then there are the ones that hover above the baseline, or even BEHIND the baseline, and you fall backwards (whether it be away from the baseline or deeper into the ad side).
Now, from the rear view, there are balls that fly well off to the left on you, and you still hit them. This should never happen if you, in-fact, have a good toss. When a toss flies that far off, catch it, and put it back up where it should be. Want proof of astray tosses? Second batch, third video, 1:00. First batch, first video, 0:55. First batch, second video, 1:00. First batch, second video, 1:10. First batch, third video, 1:45.
Now for the inconsistency of your depth? Let's look at the first and second videos of your second batch.
7 serves were hit in the first video.
1st was bad. 2nd was good. 3rd was good. 4th was bad. 5th was horrible. 6th was bad. 7th was bad.
9 serves were hit in the second video.
You failed to get a single toss inside the baseline, had a few floating BEHIND the baseline. The only one you came out almost completely on balanced was the one hit at 0:55. The one right after at 1:00 came close, but you were still finishing to your left. Neither had a toss behind the baseline (were above the baseline).
If you meticulously took down the data from these 6 videos, I guarantee you that there will be an approximate function that shows (with some outlying pieces of data, as with any real world set of data) that says the farther off your toss is, the farther to the left you fall.
There's 2 criteria for having a good toss:
1) It's consistent
2) It ALWAYS gets to EXACTLY where it needs to be
Your toss has neither of these characteristics.
How do you not see how I can say you have a bad toss? Because it leaves your hand? Because it stays within the reach of your racket? Because you consistently get strings on the ball? I'm confused how you could even have the illusion of having a good toss BEFORE even filming yourself. I'm even more confused how you can stubbornly believe that lie even AFTER seeing yourself on film. You HAVE seen your serve videos right? You HAVE attempted to analyze them yourself before you submitted them to us right? Or are you trying to have us do all the work in analyzing it then selecting the bits you like and throwing out the truths you deem ugly? Or are you going to just deny it under the pretense that they were just "warm ups"?
You want to get more pop into your serve and land farther into the court?
Lean into the court a bit with your hips. Instead, you have them sitting in the middle of your legs. Why do you not lead with your hips? 1) You've probably never been told to do so, and 2) it seems VERY stupid to lean your hips forward to hit a ball that is right above you, and it IS stupid. So your body sits back so you don't get that awkward situation where your body is a foot or two in front of the ball during contact.
You want to land into the court?
http://www.youtube.com/watch?v=rTXgMbyjMuU
http://www.youtube.com/watch?v=WRsmm0qV02o
Look how far into these two lean into the court with their hips. Look at where their toss is. Look at their contact. Compare that to yours. They launch their upper bodies into the court. You launch yours backwards. The most significant differences between your serves? The toss and the hip action. Their tosses are in the court, yours is either above the baseline or behind the court (not even in a consistent location either). Their hips lean WAY into the court and in front of their bodies. Your hips sit in the middle of your feet. There's a cause and effect for everything. The cause of your problems is your toss. You want the quickest way to improve your serve? Improve your toss. That alone will improve your serve since you can more efficiently channel the energy of your motion directly into the ball. After that, lean into the court with your hips, creating a larger load of energy to be directed into the ball.
How can you look at your service motion and say that there is anything wrong with it other than your toss? Your serve has nothing else that needs to be changed. Your motion is a solid base with which to add little improvements to (knee action, leading with the hip, shoulder rotation). But you can't do that efficiently without first improving your toss. You can have a great serve if you have a great toss and a bad motion. Even if you have a great motion, if you have a bad toss, it's all wasted and becomes a bad serve.