There's a fair amount of things and a ton of video to look at. I'm tired right now so I won't look at too much and might be able to give more advice tommorow.
- As I said there is a ton of stuff that could be commented on, so I'll start off suggesting that you actually spend some time practicing by yourself during those 2 weeks and get better control of your character. You seem to make a fair amount of technical mistakes.
- Don't be so quick on using your DJ. Being above marth with no jump is not a fun position to be in. You may get hit by not jumping every once in a while, but you're almost guaranteed to be hit if you do jump.
Also pay attention to what your opponent does - Example @0:45 the marth hits you with a Dair and then goes for an fsmash. Even though the fsmash clearly whiffed, you still went for the panic DJ a fair amount of time after the fsmash. It was a free punish from you, but because of a sort of auto-pilot response to the Dair, you lost the punish and set yourself back into a bad position.
- I see you whiff a Fair and moving towards your opponent ("committing") alot, which is really bad for your spacing and you have to make sure you're going to hit when you do that. Otherwise it is better to take that extra few steps forward and make sure to be jumping backwards or at least straight up. I think you could benefit from csticking your aerials more, but also just be a little more careful with when you throw out your Fairs in general.
- Use more ftilt and ground moves in general. In addition: Crouch cancel (into these moves or grab). Seriously... You need to abuse crouch cancel so much (use it at all), there's so many times you could do it in these games.
- If you aren't going to do proper ledgedashes, then just "walking" up on stage is often just as good or even better. I do encourage practicing quicker ledgedashes in friendlies though and you should try to refine your timing a little when you can constantly HEAR your airdodge onto the stage.
I wrote more specific points, but decided that this was the most important stuff. Maybe i'll post it back up tommorow and/or add new stuff. Plenty of stuff you can work on anyway, hope you found some of this useful.