Tap the snapshot extension button or use keyboard shortcut OptionAlt + S .

Right click → Screenshot 
Move mouse to automatically select screenshot area - click area to save screenshot.
Drag mouse to screenshot a custom area.

1. Select page content and click the snapshot browser extension button
2. Select more page content and tap the highlight button  displayed next to your selection.
3. When finished highlighting tap the "Save highlights" button or keyboard shortcut ⌘Ctrl + S .

1. Open the YouTube video transcript and wait for the transcript to display.
2. Tap the snapshot browser extension button to open the snapshot toolbar.
3. Tap the save transcript summary button  to save a video key points summary.

1. Open the YouTube video transcript ("Show transcript" button in video description).
2. Wait for the transcript to display.
3. Tap the snapshot browser extension button to open the snapshot toolbar.
4. Tap the highlight transcript button   to start a transcript highlight, tap again to stop highlight.
5. When finished tap the Save button.