overlay on top of video

i have made a video (the hard way) and the audio was recorded on a recorder instead of cam corder. i have somehow managed to match up the audio to the speaker in the video. however, when i went back to double check i noticed the first 10 seconds of video needs to be deleted.

i can extract the audio from that but the video doesn't need to be there, the speaker is counting down with his hands. i tried to place a title page OVER the video but it would not let me. what is the best way to hide the 10 sec video without deleting it?? ( if i deleted then all the audio will shift and not match up. it took two weeks to match up audio (3 sections) so i don't want to re-do that.

thank you in advance!