Only have a portion of an alternate audio source play

I'm adding a performance of a piece for sax quartet that I uploaded sheet music for and I'm trying to add the alternate audio source. I added it and manually added all the measures and everything in the video. The only issue is that I only want half of the video to play on my score because that's all I made sheets for. How do I go about doing that?

Here's the score: https://musescore.com/score/manage/media/manage?score_id=5304302

thanks!