1st stock, missed jab upb (bad spacing bro ) , read ddd's shielding, notice as soon you lost ur first stock, and ur pressuring him, alot of his body is exposed when he was shielding, u can shield poke with nair or something
your biggest problem was stop rushing so much, your constantly approaching, be patient with your kill, camp it out with fireballs (DDD sucks at approaching, luigi is more flexible on the ground than ddd.)
1:55 = why would you try to go offstage, to edgeguard him? he's on the ledge, his main options have been cut off, (you basically gave up your best position for a ****ty reward) all it takes is a simple reaction, to what hes gonna do on the ledge. be patient and youll get him
the mu is pretty straightforward, all you need to do is just space right outside his grab/ftilt range area, and constantly control the middle of the stage and push him to the ledge where he has no space, you didn't do this, since you kept rushing in and not spacing properly (these are some basics yo! )
also ur letting him land too safely, notice all the times he landed safely and u didnt punish?
dont forget to grab, if theyre shielding alot
dont force the ko, you wait for it and slowly safely chip in damage (by then bthrow can kill DDD)
ps: wall of text ftw
ps: scatt is beast for being a 14 year old wii chuk