I have a couple of waist packs from Lowepro. One, an Inverse 100 is small, good for running or climbing, is supposed to hold a camera in the center with lens (lens facing down) and 2 lenses, one on either side. I have a FF Nikon which doesn't fit in that center position, but the partitions are movable, so FF camera w lens plus one addl lens. Excellent for going light. Might be perfect for a video camera
Heavier waistpack: Lowepro AW200 (camera w lens attached plus 4 lenses plus accessories). the 200 is heavy enough loaded that I figured out how to attach for-waistpack suspenders.
I've since moved to a sports camera backpack (Clik Elite countrajour). Camera w lens available through side port. all gear behind zipper panel. Carries 2 camera bodies, 1 with lens attached and four-plus add'l lenses.
All of these come with weather covers.
Then there's all the bags I use that actually look like camera bags or briefcases. I guess the biggest is a Lowepro 'Magnum' that I have from my film days. Pretty huge. One danger: buying a bag with spots for lots of extra lenses means those spots will be shouting 'hey! buy another lens!' to you.
You know there are padded inserts that let you turn any bag into a camera bag? IMO the best non-camera bag to do this with is a diaper bag. Capacious, lots of non-padded pockets for accessories - and just being a diaper bag means it's a bit less likely to get nicked.