This animation/video is a bit simplified. In real life, a couple things are different. The part at the top of the valve (or linked via pushrods and rockers) that actually contacts the camshaft is called the tappet. Tappers can be “flat” (not literally, they still have a bit of crown) or roller style. In either case, the tappet is made of friction resistant alloy and does NOT break contact with the cam. It follows the entire lobe so there is no “striking” just rubbing. Roller tappers greatly reduce friction but increase mass. In either case, the cam and tappets are enclosed in the engine head and continually fed motor oil to reduce friction and dissipate heat.