I've installed this script a week ago on my 86U and it works exactly what a QoS system should be in my mind, so thanks for all the work you put in this project.
About your recommended priority list, right now my top priority is Gaming, so I put it above VoIP, but I have a doubt about Web Surfing and Video Streaming, is there any reason why Web Surfing should be above Video Streaming?
I believe video streaming doesn't need to be that high, because all video streaming services (Netflix, Youtube, etc) make use of buffering, so they can handle interruptions in the internet. Obviously VoIP/FaceTime + Gaming cannot handle interruptions.
If you put web surfing below video streaming then you might find yourself unnecessarily waiting longer for news web site / Facebook / Reddit to load, while your Netflix stream runs along fine. But your Netflix stream would run along fine REGARDLESS since it probably has a 10+ second buffer on it. So it's better to prioritize Web Surfing (Facebook, Reddit, Internet forums, Amazon.com) above Video Streaming.