YouTube video disappearing?

Well, I just made my new Youtube channel for my covers today.

I uploaded my Just be Friends Piano version cover up, first. It had over 40 views, haha!

And them, I uploaded my Just be Friends cover.

But.. then the Piano Version disappeared from my Uploads list. I was puzzled, because whenever I went into the "My Videos" list, it was still there!

So, I deleted my JbF-Piano Version-, and uploaded it again.

But then, lo and behold, my Just be Friends cover disappeared! D:

See it for yourselves --> Click

Have any of you encountered this problem? What should I do? D:

Here are links to both of my videos.
https://www.youtube.com/watch?v=colvPCPVV6Q
https://www.youtube.com/watch?v=uyXaZVeKy7U

I dunno, but it happened to me, too! It's mysterious!!
The strangest thing is, it only happened on my second Youtube o.o I uploaded a cover of Kokoro from NicoVideo and-- Poof! it disappeared! I don't think it's ever coming back, but you can still see it on Youtube... TTwTT
...
Oh, but on my main channel, my first video disappears for a while every time I upload something. It comes back after a few hours or so... I think the key is to upload gradually and not all at once, 'cuz all the videos on my second channel were uploaded the same week, most of them the same day... huh. o.o;; (wow, I wrote alot...)

Hmm, I'll try to do that next. Thanks for the advice~ :D