Stop video when you begin entering text

I am doing an experiment that involves presenting several videos, one after the other. While the video is going, the participant will need to enter a word and as soon as they begin entering the word, I need the video to stop. Then, when the word is entered completely they need to be able to press next and then move on to the next event (video), which will do the same thing. Currently, I cant even get it to allow me to type anything in while the video is going, let alone figure out how to have it stop when I begin entering text. Can you help?

I understand you are working with Stacie on this. Please let me know if you need any additional help.