I have two push mowers. One has the first style and the other has the second style oil dip sticks. You add the oil where the dip stick is at. I want to tell you when you add oil, the oil tend to get on the dip stick when you try to check the level.. To get a good reading on the dip stick you may have to check it 2 or 3 time. Wipe the dip stick each time. When you see the dip stick shows the same level on both sides of the stick(at least close) that is your level. The video with weedeater must be briggs and Stratton engine like my murray. That dip stick is on the muffler side near the back of the engine. Mine has the yellow cap also(I just tighten up with my hand not a wrench). I have had mowers with a cap with two little round rod sticking out the top of the cap. It was lower and more to the center of the mower..
How to open the dipstick oil cap of a Weedeater Lawnmower https://www.youtube.com/watch?v=QedmWlDfMhM
Briggs & Stratton - How to Check the Oil on your Lawn Mower https://www.youtube.com/watch?v=SR3Gkt7x0VI