okay... even though I'm not really recommended for taking ness' playstyle from, you can watch some randomness on this:
http://www.youtube.com/user/Eagleye893
//posting in video thread in a minute or two.
Eh, Neon... My playstyle ain't weird enough?
Generally safe tactics that I use when someone is on the ledge and I'm onstage:
SHFF Dair (moving somewhat near edge then retreating, timing right) > something
^Works more for higher than 100%... in fact, I do that almost only for over 100% on my opponent.
SH PKfire or FH PKfire onto a platform (such as BF) so that the fire bolt goes over the ledge and at that angle downward.
^the SH version is risky, the FH version is situational, but worth it.... you can also use PKjump, but that's more for specific occasions. It travels in a way that will almost ensure a PKfire hit if you are timing it perfectly... but it's easily seen, and also easily reacted to. I've used it less over time, but it has it's usages.
dtilt x2(3?) > Shield > something
^What I like doing lots. If I'm close enough, it's sure to do something amazing (I HAS GREAT BAITING MANEUVERS! XD) you dtilt once or twice during part of the invincibility frames of the opponent... sometimes, they will think "EH! GETUP ATTACK WIN!" and they do it... which is why i shield. The normal human reaction time doesn't counter it too well combined with many character's getups. If they don't do anything, you should have started at just the right time to get them in their non-invincible frames at least once. If only once, step back slightly and wait. If more than once, I say shield like normal. <THIS ALL DEPENDS ON SITUATION!! I'm really just thinking aloud.... That's my thought process in milliseconds. If they instead decide to jump, roll, or getup from ledge, you are almost assured a hit if you shielded. OoS nair, OoS uair, Drop shield>dsmash gets rolls (depends on character, but you can also turn-around to usmash if you want and catch some people), OoS dair, OoS bair... really, I doubt enemies will do these options. If they do, take advantage.
^sorry for rant.
I do other stuff for ledge too, but I just like those. I had to mention, because you used Fair as your opponent was on the ledge... might work with DDD, but not ness. Ness' Fair doesn't really hit below him very well... I've learned that over time.
okay, I like dash attack usage... nice... sometimes unneeded, but Oh well.
PSI MAG!! (good for most... one time, you missed an easy absorb, but I won't count it against you, since you didn't get hit)
DTILTx2 > Followup IS TOO PRO!
FH Aerials > SH aerials on higher percents (I think you didn't have too much trouble with that, but just to keep on mind)
Ftilt can kill unsuspecting victims... I liked the usage of it that you showed in the first match.
less fair, more nair/uair/bair/dair.... All of ness' aerials are good in appropriate usage (Uair is the king of landing, bair is the king of super great timing and spacing, Nair = supah speed, Fair = CAN'T TOUCH THIS!!, Dair = MINDGAMES!! SO MUCH DAMAGE and GOT SPIKED NUB!)
cool fsmash... don't disagree particularly... good in moderation, which is what you did for the most part...
Needs moar SDI (you said you have to work on momentum canceling/DI, but just putting it out there...)
On an unrelated note, Learn to play chess (exercises mind), learn to be ueber pro at using butterfly PENS (not knives; don't want people cutting themselves... If anything, a super-dull bladed butterfly knife) (SUPER AWESOME HAND/FINGER CONTROL!), and read people like books... and read books like people... wait... idk.