Shape Flexible Attendance Policies Around Video
While it's disorienting to look at a black square or a photo, there are several really good reasons that students might have their videos off, from helping with unstable Internet connections to protecting vulnerable family members.
The best course might be to honestly explain the situation. Try saying, "I feel more comfortable when I can see faces, and I hope to make this classroom a place where everyone feels safe and comfortable using video, but I also understand where we're all coming from and will never penalize you if you need to turn off your video."
See this Stanford Daily article, "Please, Let Students Turn Their Videos Off in Class" for more information on the difficulties students can face with mandatory video-on policies.
If Possible, Build In Multiple Paths to Complete Work
You might love a good live discussion--but for your students joining your course from across the world, the lively discussion might be in the middle of the night. Or a great student might have a day when the power goes out and they can't access the Internet. What do you do?
Come up with reasonable solutions that feel sustainable to you. Perhaps students could have the option to join in person or to watch the recorded discussion and post on a discussion forum in Canvas. Perhaps students can make up a lesson during office hours if they have trouble accessing the course.
Depending on the particular course and situation, don't be afraid to be more flexible than you would be in a normal quarter. Instructors during Spring 2020 cut assignments, switched from written to more casual oral projects, and used contract grading to help students control their workloads. We're not in normal times, and a little compassion can go a long way.