OwlZoom is an open-source Chrome add-on developed by lionroar07. With OwlZoom, users can easily zoom into Youtube videos. To use OwlZoom, simply select the 'Zoom' option from the Youtube Settings button on the video you wish to zoom. You can adjust the zoom level up to 2X and scale using SHIFT + ALT + arrow keys for directions.

This add-on is versatile and can be used in all three play modes on Youtube - Normal, Stage, or Full screen. Keep in mind that at 100% zoom, scaling is disabled. To return to the normal view, set the zoom level to 100% or use the shortcut SHIFT + B.