I only watched the first match of the first video and this is what I got from it. btw my sheik sucks so take all of my advice with a grain of salt seeing as I could be flat out wrong. I just felt someone had to continue critiquing. =/
Try not too dsmash at percents where it can't kill, since f-tilt is a much better option at those percents and you need dsmash to kill.
I don't find too much wrong with rolling, but don't roll into your opponent, its like asking to be punished. You can jump OOS and do whatever instead, or just shield drop to ftilt (ftilt just to have some hit boxes out so you don't get grabbed or w/e)
If you want to follow up f-tilt at low percents, I suggest grab or dash grab over dsmash.
I find it better to charge needles when they're away, rather than just shooting a single one, then wait till they land or and other oppurtunity to release them.
Try to mix up your throws and follow up depending on how they DI your previous throws. Or wait for the airdodge and punish. Or you could always just throw and charge needles (I do this when I need to be REALLY campy). You can switch between following up immediately, waiting, and charging needles, to keep them guessing.
Try nair (or utilt, especially if you're saving nair for some reason) out of f-tilt as percents where they won't get hit by upsmash anymore.
And random upsmashes or running upsmashes almost never hit.
Probably some other things I should have mentioned like how you neglect a lot of sheik's moveset, but I gave the advice I was fairly sure of. And you did stuff well too, but I don't care to mention any of it. =P
You're sheik looks interesting so I feel motivated to try another critique.
edit: You're sheik is too good! I love the style you play with and being able to keep up and even beat santi is ****ing beast. I can't really comment on your sheik, because its so much better than mine, but I can say light's vids should be considered for the reputable player vids that East was just talking about.
Ok, one comment. Don't rapid jab on stage. jab,jab, (crouch?) grab won't get you punished as bad.