Go to edit mode of the loop and unfold the node where you want to record film or sound. Put the marker where you want your film to end up. Click the plus sign to make it a cross. The possibility to record film and sound will both appear. Click the symbol you want and follow the instructions. When you are done you can save the node and keep working on something else while the film or sound is uploaded. It works the same way when you record film or sound in a hub panel.