This video demonstrates how to buck a larger tree when there is extreme top pressure. It is important to note that this method may not work on smaller diameter trees. because they simply do not have the volume of wood that allows a saw operator to start at the top and saw down through it. As long as the saw operators bar is reaching clear through the log or they have cut the far side first....then the next step is to simply saw down through the log starting at the top and coming out the bottom. That being said ...there is a chance that the cut can get to much pressure and even get the saw stuck in a very bad position. That is why it is important to pay attention as you are cutting and run the saw back and forth to widen the curf a little. If the saw operator begins to feel to much pressure , then it's very important to pull the saw out and finish by coming up from the bottom. This should only be done if there is not a lot of wood on the bottom. If there is a lot of wood on the bottom it may be necessary ( if it's to tight to continue down through the top) ...then bore through on the bottom ( leaving a little strap of wood on the bottom) and then come up. The idea is to get the log bucked off without splitting it . Leaving a strap on the bottom and coming up will help hold things in place longer and hopefully prevent any splitting, but there is a chance of getting the saw stuck if the chainsaw operator does not leave a chunk of wood between the top and bottom cuts. This chunk should not be any wider then a hinge width ( 2...or 3 inches). Once the saw operator has it cut up with only two or three inches between the top and the bottom , then the very bottom strap can be cut ( a lot of times it just breaks naturally when cutting upwards to meet the top cut) .