I have been recording synchronous sessions for about five years now so the task was easy. I think the challenges I have had in the past when teaching is actually REMEMBERING to press the record button when you start teaching. Some of the other challenges of synchronous sessions is getting students to actually show up. I have started to offer incentives like point as well as playing songs that students request to hear in the beginning (as long as they were appropriate for the classroom).
Here is a link to one of my recordings in which I am reviewing important Final Exam information: http://gavirtualschool.adobeconnect.com/p99lwwbbl83/
I believe that synchronous learning is one of the most powerful tools in online learning especially in Mathematics. While watching the recordings are nice, there is nothing more powerful than the student being able to get real time help from teachers.