Yeah, I agree. There are many reason why this will happen. Facebook videos have more views for easy reasons.
The first one is that there's the auto-play function on. How many times did it happen to you that you're scrolling your Facebook homepage with your iPhone, maybe because you're bored, and a video stars without you playing play? sometimes you just skip, but still, the video has started. And some other times, since it already has started, sometimes you see something that catches your attention (some are smart with the golden 5 secs..) and you actually watch the whole thing. Something that wouldn't happen on YouTube, since you open the video only if you're already interested, orit doesn't happen that you're watching
The second reason is that it's so much easier to share. You already see it on your friend's page, how does it take to press like and share? 1 sec. Or how does it take to tag 5-6 friends? Maybe because it's funny, or because it reminds you of something you have in common with your friends. They're gonna do the same, and it becomes viral. On YouTube it's more complicated. YT doesn't really have feeds, so when you share it it's usually somewhere else, like Facebook. And Facebook is smart. There's not autoplay for YouTube videos, or that much of a preview. You can't even watching by pressing play like it used to be, you have to click it and open another page, then watch it. Too much time. Those few seconds are way too much time that make you lose thousands of views.
The third reason is that there's so many more Facebook accounts. Not just for the number, there are a lot on YouTube as well, but many of them are not used, or maybe they use it every few days and don't really do anything with it: don't care about the look, the name, or anything. Many don't even remember they have it, many don't have it at all, so they can't even comment or like. With Facebook it's a whole another story. Everyone has their profile updated, at least with as many informations as they're willing to share. The thing that you share a Facebook video on Facebook, and a Youtube video still on Facebook says a lot.
Fourth reason is that Facebook is easier than YouTube. Yeah, don't think with your own head, if you're here you're obviously good enough to have a YouTube channel and know the features. But, for example, my dad is an amazing guitar player. He uses a lot Facebook, to stay in contact with old friends that he doesn't see from many years, or to join musicians group to talk about guitars and stuff, ecc. Sometimes when he's bored he uses his phone, and old Nokia Lumia, and he record himself covering the Zeppelin, his favorite band. Then, easily and quickly, he uploads it on Facebook, and many of his friends comment on it, share it with other friends, in musician groups with thousand of people ecc. Then I asked him why doesn't he start to upload on YouTube. He had no clue how to do it. He didn't even know he had an account. He does have a gmail, but he didn't know it was connected. You can use the same email and password and have an account with it. Or he didn't know what to put in the description, how it's gonna look etc. So he was not gonna do it, until I helped him. So many people are like that.
With this said, yeah, I agree that Facebook will be YouTube's death. I mean, YouTube will probably never die. But you can already see a big difference. That's why many famous youtubers are already posting videos on Facebook, or at least a preview. The moment when Facebook will start to pay users like YouTube, it'll be a point of change. I believe they'll also change many things. Like they might introduce a whole new section on someone's profile only about the videos. That's why it's smart to start making Facebook videos now, to grow audience, and be ready for the change.
I honestly prefer YouTube, by far, so I hope they'll find a solution. They obviously already noticed this problem and already thinking about what to do about it, what to introduce new to attract users. And I really hope they'll find the right thing. Because if it keeps going this way, YouTube will have a brutal decrease of traffic very soon. But be ready. In the end, everything that has a beginning has an end.