Although the water looks quite murky in the video, visibility was around 2 feet or so, which is more than adequate for viewing from above.
The fish in the videos are chum - we did see coho as well, which are a solid red colour, but they preferred the safety of deeper waters and wider streams.
Salmon never cease to amaze me. Imagine spending years never touching anything except for the ocean itself, then migrating into and breathing a corrosive feeling freshwater fluid. As you move into smaller streams, you try to keep away from the rocks that nick and scratch your thin skin, but weeks of navigating the shallows have you mentally and physically exhausted. The stream doesn't stop moving at night, and neither can you. You see moving shadows above the water, and you're not sure if they are a bird or bear looking for a quick meal, or just some innocuous human watching you, but you dart away to be safe. The stream seems to end - at least the visible part of it, anyway. Water is still proceeding in the form of a waterfall, and you take a blind leap, hoping you jumped far enough, that what you will land on is water as well. Failure could mean getting tossed headfirst onto a rock that has claimed the lives of many before you. You finally find a spawning pool where you find other survivors. The act of spawning itself is what probably will do you in. When you spawn, not only do you release your milt or eggs, but also your will to live. You have fulfilled your purpose in life...and now you have a purpose in death, that of feeding the birds and other scavengers who in turn feed the forest.