This behavior has changed several times since it was first introduced. In some cases, the original behavior was retained, in some cases, it has been improved and updated. Please see the instructions below for the specific versions.
Appearance and behavior in Version 2.0
In Version 2.0, the ROI icon will appear as shown above. To add multiple ROI's in your video you have to left-click, hold and drag the first box. It will be RED in color. To draw the second box, you had to press the Control [CTRL] key then left-click, hold and drag additional boxes. New boxes will be BLUE, GREEN, ORANGE, YELLOW, PINK, then RED with this sequence repeating. Between each ROI, you have to wait for the measurement calculations to complete before starting to position the next ROI.
Appearance and behavior in Version 2.1
In Version 2.1, the ROI Icons were changed to those shown above. In this version, a "Persist" mode was added.
When the Motion Amplification® software is set to "Standard Mode", your icon will look like this: 
. In this mode, you add multiple ROIs by following the same procedure as described above for Version 2.0.
When you click on the down arrow between the two icons, your icon will change to this: 
. To draw ROIs in this mode, you only need to left-click, hold and d
rag with your mouse. Every time you release, an ROI will appear. When you click another location, you will begin drawing a new ROI. Between each ROI, you have to wait for the measurement calculations to complete before starting to position the next ROI.
To switch between the two, simply click on the arrow to the right of the ROI icon, 
. Choose the mode you would like to activate and click on the name to close the menu:
Appearance and behavior in Version 2.2
In Version 2.2, Standard Mode was changed to "Independent Mode" as shown above. The behavior is still as described in Version 2.0 above, only the name was changed. "Persist Mode" behaves as described in the Version 2.1 section above.
Appearance and behavior in Version 2.3 and Version 2.4
In Version 2.3, the ROI Icon has returned to the original design. However, the behavior is as described under "Persist Mode" in Version 2.1 above. Simply left-click, hold and drag to add ROIs to the video. You can still hold the CTRL, left-click and hold to draw multiple ROIs as well.
You can now click the "Cancel" button as the first measurements are calculated. Early measurements will be suspended until all of the ROIs are placed. Allow the measurements to calculate after placing your LAST ROI and all previously placed ROIs will have their measurements calculated at once saving you time.
For example, if you want to place four ROIs in your video, you can left-click, hold and drag to place the first ROI. As the measurement dialog appears, click "Cancel" and place the second and third ROIs in this same manner. When you place the fourth ROI, allow the measurements to calculate and all four will be presented when done.
Appearance and behavior in Version 2.5
In Version 2.5, the order of the two ROI icons is reversed. Delete is on the left and the Type of ROI selection is on the right. In this mode, you place ROIs by left-clicking, hold and drag in the area where you want to ROI. You can place multiple ROIs by continuing this process everywhere you want an ROI. You can suspend the measurement calculations and complete them with the last ROI placed.
In this version, you have two new ROI types, the “Horizontal Shaft” and the “Vertical Shaft” measurement tools. As the icons indicate, you will be able to measure shaft movement on a shaft which is recorded horizontally using the Horizontal Shaft tool. Shafts recorded in a vertical orientation are measured using the Vertical Shaft tool.
Appearance and behavior in Version 3.0
The ROI Icons appearance is unchanged in Version 3.0, but there is a new “Transient” ROI tool.
This type of ROI will track translational movement and show you the path of such motion.
PURPLE was introduced as a 7th color in the sequence in this version. Now the color cycle, RED, BLUE, GREEN, ORANGE, YELLOW, PINK, PURPLE, RED, will repeat.
Related Articles:
What is an ROI in Motion Amplification® lingo?