I would like to help you with your question, but it is a very personal question that only one can answer. Perhaps it will help if I break down the question for you. Your "impressions" refer to how you felt as you watched the video. What did you notice about the way Laurence Fishbourne portrayed Othello? Did he make the character seem more real to you than when you read the play? Was Shakespeare's language easier for you to understand when you heard it rather than read it--and when you heard it acted by a fine actor? These are the kinds of things you could include in "impressions."
On the other hand, maybe the film was difficult for you to understand. That would be an impression also. You might have liked parts of it (perhaps the action, the costumes, or the settings), but perhaps you still had difficulty keeping the characters straight.
Presumably you watched the entire video because your homework question asked you how your impressions changed. That means: Did you like the movie more or less as it went on? Did you find you understood it more? Did you enjoy it? Did you feel strongly for Othello when he was duped by Iago? Did you feel strongly for Desdemona? What other character portrayals did you like or dislike?
Only you can determine what your own "impressions" are, but I hope by breaking down the kinds of things you might include in these impressions I've helped a little.
Good luck, and don't hesitate to ask another question if this is still unclear.