Play/Pause button will toggle the playing of video
Clear Frame Range clears and selected from range on playback
Select annotation drop down chooses the tool to use
Annotation navigation will choose next/previous annotation in the group
Clicking on the group button switches the displayed annotation group and the group annotations are added to.
The single image selector sets the annotation to apply to just the current image (shown on +/- 5 frames)
The [ and ] indicators beside that add left/right boundaries to the image to choose a range.
Delete annotation will remove an annotation