Hylian, I'm not going to pretend like I'm a pro or anything (still trying to find solid practice in the area), but I really keyed in on this comment after watching your vids. Most of the time when you tried to approach with spaced aerials, he shield grabbed you. However, when used aerials and finished above/just behind him, he couldn't get the grab and had to drop his shield and turn around, which gave you time to Up B to safety. He didn't really punish you when you got to the back of his shield. Also, he didn't really have an answer to your Up B, and you seemed to get away with Up B -> DAir behind him fairly comfortably.I will add two things you can do that might help. I didn't see you do any landing nairs. try to land behind DDD with nair. It sets up well for a combo, or a grab at low %.
Not sure if this works all the time, (again, I don't know the matchup) but that was the main thing I noticed after watching your vids.