The top that I seen doesn't look like they're gonna fall out. She has big boobs but that doesn't mean they're gonna fall out.
I've seen enough swimsuit malfunctions to know it can happen, especially on waterslides.
Besides, looking like and falling out are different. There is a point of too much cleavage. If there wasn't, people would go to water parks with stickers over their areolas and nipples.
I had my wife watch the video. She thinks what she is wearing is fine, but that her top is too small.