I have professional experience in attending courts, to provide professional opinions, sort of expert evidence. In addition I used to be a panel member of lower tribunals when I sat with a judge to hear some cases. I can emphasize the following points already provided by others.
1. You are a witness. You have not committed the crime. You are not on trial. Defence will try to make you feel like that.
2. Always face the judge/ magistrate and not the defence lawyer. One useful technique is to face your feet toward the judge when standing/ sitting. You turn your head or body to listen to the defence if you want to. By that way you will always look at the judge when answering questions. You are providing information to the judge and not to the defence.
3. Read your witness statement and be familiar with what you have written.
3. Defence do not ask questions. They make statements and ask you yes or no. You do not have to say yes or no. You can provide a long answer.
4. Finally, do not get emotionally attached to the case. Win or lose is not your concern. Just tell as it is.
Finally, it is really grateful that you have submitted this video and get at least one ba***** to come to court.