Youtube is very slow for me at work, but I looked at some of my most disliked matchups, namely Snake.
You had immediately off the bat an opportunity to grab Snake out of his Cypher, granting you an early KO. You also got hit by his dash very often. When a Snake uses his Nikita (he really shouldn't that often in a 1v1 situation besides maybe edgeguarding), don't approach him on the ground, as you'll roll into the dropped missile.
edit: finished watching that match, you did much better later on. I might suggest using Inhale more often - it catches his dash attack, plus is a good way to break someone's rhythm, especially a camper like Snake.
edit 2: watching the Meta Knight match, you are trying Fsmash way too much and getting punished every time. The Meta Knight also isn't fantastic - he's spamming his KO moves and diminishing them. Against a smarter Meta Knight, you would have been KO'd much earlier due to those moves actually hitting at full strength.
Abuse inhale versus Meta Knights that like to approach aggressively on the ground - he will get inhaled every time unless he stops and approaches with his B moves. A few opportunites were missed where you could have star KO'd with up tilt.
edit 3: in general, I think you should be using more of his moveset. Less smashes, more tilts. Inhale more. Up tilt is a very good KO move, down tilt very good at poking and playing keep away.
edit 4: against Toon Link, I have the same problems you do playing against him. I really hate him, but anyway... you dodge projectiles better than me, so I can't comment on that. You began to be a little predictable with your falling onto the opponent with Bair, and thus were punished a few times. Other than that, your opponent was Toon Link, a little tough for Dedede.
