My suggestion is that if you’re doing fixed interviews, uploading your content at 8 Mbs is fine. But if you have a lot of moving cameras, hand-held shots or quick cutting/dissolves, this is never going to work. In such a case, you can do two things:

1) Render your content at 25+ Mbs and make YouTube figure out all the parts of your content that require higher bandwidth (dissolves/fast motion).

2) Render your own 8 Mbs versions and alter your dissolves and color or edits so that it looks as good as it can.

Personally, I always do “A”. Why? Because Youtube’s algorithms for down-rezzing highly complex footage are far better than most video editors. And while it’s not perfect, I’m usually nominally more happy with Youtube’s results. 

If there’s concerns, it also helps if you upload in a codec which has little compression like ProRes. This way Youtube has maximum latitude to do whatever number crunching it needs to. This kind of setting takes a while to upload and process, but I find this makes for better results than trying to solve these issues on your own and having to re-render footage time and again.