Video background:
On the timeline, move the playhead to the desired position on the video track, then click Freeze Frame in the toolbar above.
The frame at the selected time point will be added as a 3-second background image scene and inserted between the two video clips. The image will also be automatically downloaded to your computer.
Video layer:
First, open the Timeline panel.
Here, move the playhead to the desired position on the video track, then right-click on the video layer and click Freeze Frame.