I did watch that video but what am I missing? Its gotta be user error. not blaming the equipment.
What type of cartos are you using? Boge? Smoktech? Other? The Boge's seem to have thicker polyfill, but I prefer this as it is more difficult to flood the carto. I personally punch 4 holes, 2 high and 2 low, and this seems to work very well with any juice I have tried. The size of holes matter too, you have to experiment to find out what works best for you.
Also, what type of carto punch are you using?