I was on a call with an education technologist, and I noticed she had a very good trick for keeping the flow of communication going while expressing her agreement. Instead of saying "uh-huh" at regular intervals (which can interrupt the flow because of audio lag), she would just give thumbs-up to show her agreement. I've started doing this as well and have found that it precludes a lot of the "oh no — oh, I was just going to say yes I understand" comments that often happen in video calls.