Why Slo-Mo a whole run? What are you trying to show with that? Seems strange.
Instead I would:
Show run at normal speed.
Pick 1 thing to fix...show the issue in 1 slow mo segment, likely no more then a gate, unless it is a "line issue" then 3 gates is likley needed
Dont only tell that what to do...tell them how. Currently you just say "what".
Also likley good to do the same thing, with 1 slo mo segment showing some postive stuff as well...again say "why it is good"
Show run again at normal speed so the athelete can hopefully see what you saw from the slo mo at speed now.
The 6yo old.
I am fundamentally against documenting by way of video or writing anything negative for kids of this age. It is just fodder for pushy parents, and the kids will just hear you voice over and over. For kids, just shoot the video, overlay some cool music, and encourage..."going for it here", " nice tuck there", "agressive here"...."having fun there, whoo hoo"...that kind of thing.
Price point: Not much, too many people willing to stand on the hill and shoot video for free. So go for videos for free beers etc. You wont get much else.