Just a thought on double ended zippers. It is a mark of the quality of Tom Bihn bags that there is a zip pull at each end of most zippers. However, when I watch Youtube videos, I notice that reviewers always, without exception, pull one zip pull from each end so that they meet in the middle. This is an obvious way to do it, and it appeals to my innate love of symmetry, but it is the least secure way of doing things. In the days when I was Slim Able-bod i used to ride both a Cannondale mountain bike and a Buell motor-cycle. If you ride either, at speed, the wind will catch a zipper, so zipped, and pull it open, guaranteed. Equally,a pick-pocket can easily pull a zip, so zipped, open (especially when you are NOT riding at speed!). This problem gets markedly worse as zips get older and loosen up. However, if you pull both zippers to one end or the other, then it won't 'blow open' half as easily, and it is harder for pick-pockets.
P.S. This is not a dig at any particular videographers, this is a universal thing - everyone seems to do it, even the best of the best, our very own film star Maverick!