What I've done in these cases is this:
1) Unsync video and audio
2) In the video, split (use the razor tool) just before and after the subtitles - er... words

appear -.
3) Delete the worded part.
4) Split the video again by one frame, and export the frame to a bitmap (JPEG or whatever). Then import it, and make a clip out of it. Paste it in the space that you had left.