fix: ensure that video buffers are empty before closing channels

internal/video/video.go

@@ -139,6 +139,13 @@ func (v *Video) Join() (<-chan []byte, string, func()) {
 		v.mu.Lock()
 		defer v.mu.Unlock()
 
+		// Close the channel
+		close(v.ivfListeners[myID])
+		// Consume any pending frames
+		for _ := range v.ivfListeners[myID] {
+			// do nothing
+		}
+
 		delete(v.ivfListeners, myID)
 	}
 }