back in the day on my old XP desktop I held onto til Windows 8 or something, video processing and upload took hours. so yeah, I feel ya, on that.
I think for what you were trying to communicate, you made good choices. speeding it up like that, with that music and some interesting text remarks mixed in in creative ways, it all fit really well together. I also liked the way you ended it, sucking wind after the music.
I would just say, from general comments my friends have made is that most people don't have the attention span for anything longer than 3-5 minutes. so if you're committed to a particular song like that one, you might look for segues in the music to fade it out or cut it off to shorten it up. again, speaking in the general case.
the other thing to realize is that anyone that hasn't ridden those trails (and even some that have) may not appreciate the more subtle features and sections you like. you rode it. you know what it feels like, so the video is much more visceral for you. for most others, especially those who don't ride, it's just a line of dirt moving around on the screen. not sure what you can do with that, except lower your expectations of others' responses. I make my videos for me. sometimes people who were on that ride may get some of the inside jokes, but usually not. I just don't worry about it, anymore.
lastly, I would have liked to have seen some of the downhills and bobsled runs at only 1x speed, being a mtb nerd. but that would have thrown off timing to the song and you would have to make cuts elsewhere.