Creating a video while driving isn’t the safest behavior in the world, I don’t think, but …
The idea of making use of small amounts of time to learn English is a good one, I think. Too often we put off doing something useful because we don’t have enough time. Usually I think it is an excuse rather than a real reason, but if we look at all the five minute time slots that we have empty, there is probably plenty of time for us to learn anything we want to learn — including English.
Can a beginner learn much in 5 minutes? Yes. If we think about the presentation portion of a lesson, 5 minutes is a lot. We can present almost any grammar point in that amount of time. It is plenty of time to present a dialogue and even practice it several times. The problem that I see is that the beginner may not know how to build on that five minutes. That is where technology can come in. Podcasts, videos, games, and other tools can provide that 5-minute chunk of learning and they are available later for the learner to go back and refer to again. I think it is much more likely that a student would review a 5-minute video than a one hour video, much less a one hour lecture!
More advanced students can fine-tune their langauge in a brief amount of time. Again, technology makes it more feasible. If I have trouble with verb tenses in conditionals, for instance, a 5-minute audio or video could help me really focus on that particular point and I could make real progress in a short amount of time.
Sometimes the short activities are the most fun, and often they provide an opportunity for real learning. Mini-lessons can be more helpful than an hour-long class on the same subject. We can only absorb so much at any one time. I would prefer to see my students make use of the odd bits of time that they have than to have them dedicate two hours once a week outside of class studying English. I think the more frequent shorter time periods are more effective.