You can zoom in/out of your canvas to check your project from a different perspective.
How does it work?
There are two options on how to do it:
1) Using the mouse.
2) Touchpad (drag by two fingers up or down).
It's crucial about where your pointer (mouse icon) is located. Once you start zooming, then you will go in that direction.
In case you want to see the default view of your video, simply click on "Fit to screen" (located above the canvas).