Hmm....
First, I'd like to mention my lack of posting is because of past lack of time....I come and go randomly.
First Vid:
Pros: Nice that you realized what DK's main game is: Grab->Uthrow->Air wrecking. Getting under air fighters and fighting fire with fire is a good strategy. I love the SH Bairs. Keeps him on his toes. Loved the Bair combos
Cons: 2:23, he was way open to be struck. I noticed a bit of reliance on DownB. Yeah, I love it too, and its great to get yourself out of an aerial jam. Just be careful how you use it against longer ranged air game I.E Marth >.<
More eggs would be nice, but then again I use eggs as manipulators. Also good for guiding your opponents when they're recovering. Egg throwing is difficult at first, but very useful later on (especially if you can short toss them to break shield grabbers!)
More Fairs would probably bring more power to the table than Bairs, though Bairs are good for constant pressure.
Surprised you didn't try any throws of your own on big ol' DK. His size makes up for the strange range of Yoshi's throws. Remember charge throw grabs only from the farthest half of his tongue at the beginning of his animation. Actually, both throws do.
Please, do NOT use Forward+B unless you're stalling towards the edge. Just as they think you're gonna get to the ground, use it to pop up and throw off their edgeguard. Its not perfect, but can be useful.
Second Vid:
Pros:Nice Edgeguard at :55! More attempts at Fairs. Comboability much more noticable here! More Dtilts seen too. (remember, Dtilt is always a set distance attack when not Crouch Canceled. Very useful for getting some space between you and your opponent).
Cons: YIKES! 1:32, downB was NOT the best of ideas. So many deaths I've suffered from trying to beat someone to an edgehog. Best to avoid that situation. A few missed Fairs, but more in Vid 1. Remember to roll R-cancel->sideroll right after to try and avoid a shieldgrab. Even R-Cancel->Down C-stick to beat them to the punch.
He got you on the shieldgrabs big time. Overall DK's game was beter than in Vid 1. Try aerial neutralBs to throw off his shieldgrabbing ways. Egg Lay is an awesome mind game move when mixed up within matches.
Side Notes: I've noticed you do much better on the offensive, rather than waiting to predict DK's moves. Keep on his toes more and you'll do better!
I also noticed you tried to EdgeEgg. That's definitely a good move, but very risky for the reason you died on your last life.
Edge recovery woudl be more useful if you utilitzed Yoshi's DJ tanking abilities. Drop and double jump to tank their attacks and retaliate with a nair if youre right on them.
Third Vid:
Pros:Nice Egg Rifling (That's what I call the Edge Egging now n_n). Sweet UpSmash near the end! Noticed some nice uair juggling at the end! Overall good moves on all 3 vids.
Cons: Too much Down B at the beginning got you punished. I'd suggest only using it for edgehogging from recovery or if you're absolutely sure you'll punish them for attempting aerial game. I'm guessing at 1:08 you attempted to DJC into him. Good move, but a little risky against DK's best air attack
1:45 you ate his foot big time. When recovering from the edge try to keep some sort of defensive measure ready. Fair at that point could have helped if not saved you a few seconds of life. Or in all cases when in doubt, Nair n_n
Side Notes: Remember after 100% or so, Yoshi's tanking abilities go downhill with double jumps. However, they're not all gone at that point.
Overall: It's a good Yoshi, but seems a little lax when it comes to putting pressure on DK. Yoshi's a good counter against DK since he's a bigger target. Target to Eggs, dtilt, and fairs. Just up the protection factor on your air game with more Nairs, keep your feet on the ground more rather than fully DJing, and follow up more things, and you'll be greater!
Overall Rating: 8/10 from what I've seen!