You want to save the frame you want to hold as a still image and then add it back to the timeline for the duration you want to hold it for. Here are the instructions:

1. Find the place you want to hold the frame and press the S key to split the video.
2. Then go to the preview window change the preview quality to Best.
3. Next right click on the preview window and select Display at Project Size from the context menu.
4. Then press the diskette icon next to the preview window and save the picture as a PNG or JPG file.
5. Now reverse the process by selecting Preview Quality and right lick on the preview windows and deselect Display at Project Size.
6. Finally make room for the image on the timeline at the point you made the split and find the image you just saved in the Media Pool and drop it where you just made room.

When played this will make the video appear to freeze and then start again.

~jr