Later, when your editor comes to check your notes, he simply has to click the timecode and is brought to the exact point you wanted him to make the change. The editor can also import these notes into their video editing software such as Final Cut Pro X or Adobe Premiere with those same timecodes intact so that keep track of your edits.
If necessary, they can also reply and react to your notes from within the Frame.io software.
All of these messages can be alerted to you by email so that you know when the editor might have more questions or need clarification. This can also be turned off if you receive too many messages.