Nice one!
Length. Better to break out video's into 2.5 minute clips and release individually. Youtube statistics indicate that humans now have such limited attention spans and want everything immediately thier interest will not be held beyond that period of time.
Music choice on boat video. Fast tempo used on a basic hover shot where the action does not mimic the tempo / beat of the music. Slow pacing of scenes are better "paired" with similar pacing of sound track.
Multiple angle shots of same area spliced into one video keeps interest. Plan shot lists beforehand. There are some tried and true basic shots that work in many conditions. Fly over, Fly up, Fly down, Half Circle , Full Circle , Hover , Fly up close , Fly Up far , Profile fly along, etc