I got Hoover Type A bags, three for 97 cents. The attachment hole is at the end, the end I cut open to slip over the vent hose. How you would handle that would depend on the bag you had, of course. My dryer has a moisture sensor that cuts it off when the clothes reach a certain dryness, and it runs about as long as its initial time estimate which itself is unchanged from before I installed the bag, so the bag isn't restricting air flow significantly, or even noticeably. Indeed, the hand test says air escapes through its paper body very easily though it catches the lint quite well, which is what vacuum bags are designed to do when used in vacuums. It has not blown off the hose.
Thanks for your question. Please feel free to ask any others you may have.