Marth sucks at getting back on the ledge. His options are very limited and people can camp him there if they can react properly.
You're generally more educated than to make ignorant posts like this. Not only is this only half true (Marth has an exceptional amount of proactive and reactive options for ledge), but your statement is also half true for most character's without extraordinary recovery abilities.
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Anyway, to the OP:
Nice. You've definitely persuaded me use the ledge jump more often. I've ALWAYS known it's something I should do, but this vid will probably help me break bad habits.
You can also air-dodge after ledge jumping (obviously)
You can also grab the edge again after ledge hopping without landing (obviously)
It's slightly important to note that you keep you lag from Dolphin Slash if you don't perform another action in mid-air before landing.
Nicely done though. Maybe throw in a spike from ledge and an actaul Bair edgeguard. Also, a Dolphin Slash stage spike.
You also might have wanted to show how on other stages that aren't Final Destination like Battlefield and FD, how Dolphin Slash and Fair are good for stage spiking. This works on FD too, but from Battlefield, you can trigger the Dolphin Slash immediately after the drop to stage spike a near opponent without worrying about getting caught under the stage.
Also, one of my favorite tactics, especially against edgeguarders, is to drop and up air, either falling or rising, or Uair through the stage.
That's about it. Still a great vid.