Exchanges of student produced videos is a great way to get around this. Not long, involved videos that take days to produce, but more spontaneous brief videos that can be produced easily in the class, or at home in a few thoughtful minutes. I think of it as an engaging way to enhance and complement ordinary Facebook text posts.
In our current two courses between students at the Central University of Tibetan Studies in Sarnath India, and the U of Washington Bothell, and the U of North Carolina Asheville, students are twelve and a half hours, and nine and a half hours apart, respectively. So they started off with posting brief questions to each other on a closed Facebook page, inviting Facebook written responses, and producing short videos to share introductory background info, like "one thing you may not know about Tibetan culture is...."
Instructors can also use videos to do self- introductions to both sets of students, and help launch the course. You will see examples of all three below. I find it is a great way to immediately personalize the experience, even if you are half a day into the future, or the past!