UX enhancement

client/renderer.js

@@ -110,6 +110,7 @@ getSourcesBtn.addEventListener('click', async () => {
             sourcesGrid.classList.add('single-item');
             selectedVideoSourceId = sources[0].id;
             sourcesGrid.firstChild.classList.add('selected');
+            startPreview(selectedVideoSourceId);
             startBtn.disabled = false;
         } else {
             sourcesGrid.classList.remove('single-item');