Back in the day when the choice was the BVM plastic bottle unit and I designed the CAT the whole ethos was to ensure that the fittings, bore and flow rates were all able to support the draws etc and the unit was able to sustain these criteria. If you read Oli's original thread on this which is still on his web site you will see this was an issue I tacked a long time ago.
Fortunately most now ensure fittings are as large as possible so that is a good thing, even now after stopping my involvement in this hobby I still have customers who buy my barbs from me to use in installations as they are still one of the most free flowing for the given metric thread size.
Looking at the images the first video is one of my DCAT units which Sandor 'modified' so I'm flattered
marcs