Update videocapture_basic.cpp

I believe you are using the wrong version of open() on line 28 - adding deviceID + appId together. It's better to use the new version of .open() taking two integers as parameter.

samples/cpp/videocapture_basic.cpp

@@ -25,7 +25,7 @@ int main(int, char**)
     int deviceID = 0;             // 0 = open default camera
     int apiID = cv::CAP_ANY;      // 0 = autodetect default API
     // open selected camera using selected API
-    cap.open(deviceID + apiID);
+    cap.open(deviceID, apiID);
     // check if we succeeded
     if (!cap.isOpened()) {
         cerr << "ERROR! Unable to open camera\n";