A1) webOS TV apps can play only one video at a time. For more information, please refer to this FAQ.
A2) LG Smart TV monitors can also use the Developer Mode app from the LG Content Store. Please refer to App Testing with Developer Mode App.
A3) We do not guarantee the compatibility of webOS TV apps with webOS OSE resources. For webOS TV apps, please use webOS TV resources in this website only. Thank you.