When a wave is created on two sides of a medium, it meets in the middle the wave becomes double the size of the two that met. When they pass through each other, and then reduce down to their original sizes.
When two waves pass through each other but one is a trough and one is a crest, and once they meet, the briefly become flat in one spot. After they pass through one another they continue down the medium.
A standing wave is when a medium is destructive but progressively gets faster and smaller, creating still spots called “nodes”. In our video you can see 4 nodes (in the last few seconds of the video). This is also where the peaks do not move spatially.