I did watch to the ending, the person waking up. However, since the rest of the video contained no backwards flowing water, and no backwards driving cars and that it did not seem to suggest that this was a backwards video, I don't understand how the reverse waterfall would be explained in the ending.
I am assuming this was someone viewing a dream and then they were woken by the alarm. We do not dream backwards, so maybe you could explain to me what you mean that the ending explains the reverse waterfall please.
A film making friend of mine, once did an entire video film backwards, but that was clearly meant to be that way all the way through, and the ending did explain that.
I know that sometimes when we film a scene, it looks better in reverse due to it moving away, rather than moving into the closeup. However, when that involves people walking or cars driving or water flowing, it is mostly best not to reverse those things, unless there is a valid self-explanatory reason, revealed in the film.