The perfect screencast doesn't exist. Time to stop trying to make one! Make your efforts a One and Done- the best screencast is a finished one!
Distractions and the unexpected are going to happen. If your neighbor mows the lawn or UPS rings your doorbell, acknowledge it and have fun with it. Kids love to see our human side!
Create your own quiet space, get headphones with a microphone. Post a "Recording: Do Not Disturb" sign on your door. Find a room with no one in it!
Make your screencasts mini-bits (1-3 minutes) to speed up the process. The shorter they are, the more motivated your students will be to press play!
Consider GROUP feedback for common errors that would benefit many students at one time. Then share the feedback with the group that can review it together.