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On the right side of the view is a toolbar for managing the video recording. There is also a button to allow the user to take a screenshot snapshot that can be inserted into the notes. When the screenshot snapshot is taken, a new window will appear to so the user can crop the photo to the correct size.
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Once the smartphone app is open, Ben can draw the diagram using the touchscreen on his phone. The canvas in his notes will show a live view of his diagram. Ben can choose from a limited selection of colors, draw lines with a single finger, and do bitmap erase with a single finger. He can also zoom in by using standard pinch to zoom, and navigate around the zoomed in image by either using the grabby hand or dragging with two fingers. However, adding text on a small phone screen would be slow, so instead the user can take advantage of his computer's keyboard to add text as necessary.
By clicking on the image in the notes webapp, Ben brings up a pane that lets him add text labels to his diagram, and drag those around. The controls on the side of this pane allow Ben to insert labels, move them around, navigate around the diagram, and undo or redo actions. If Ben finishes editing the image and wants to come back to it later, clicking the image in the webapp will bring it back up for editing in a smartphone.
Bringing up If Ben opens the app on your his phone, it will pop a canvas into any notes that Ben has open even if he didn't click the drawing icon first.
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Safety: Once again, the design is fairly safe: It's easy to correct errors in creating or naming notes and categories, and deletion of notes requires a confirmation. You can rely on the undo/redo stream to correct errors within a single editing session. The least safe part of the process is in the diagramming app, since there is no undo/redo in the smartphone drawing part of it. For this, users will have to rely on using the eraser tool within the app. There is also a potential for mode errors, since touching the phone screen can either draw or erase depending which tool is selected, and unlike a computer there is no cursor to make the mode very visible.