The exact length varies from video to video depending on what needs to be said. The pacing, the genre, the visuals and voiceover all play a part in the final length. The most common length will be between one and 2 minutes, but on occasion they can be between 2 and 3. The sweet spot for video engagement is between 1 and 2 minutes, because it gives you enough time to say what is needed, engage the reader to want to know more, but then get to the CTA call to action at the end before they loose interest. That’s why sometimes even shorter videos have better click through rates. Action & adventure books tend to be shorter with lots of visual action, whereas emotional and deep books tend to need longer trailers. So, in summary, length all depends on the kind of book you have written, and I will do my best to find the perfect length to match its essence for maximum engagement.