anooprj Use internet download manager in your PC. If videos are not detected by IDM then try using 1DM app on your mobile.
https://play.google.com/store/apps/details?id=idm.internet.download.manager
In 1DM app there’s an inbuilt browser. Open the applied root website using the inbuilt browser and play the video. 1DM will automatically detect all the resolutions available for the video. You can see this on the top right corner. From there you can select the video with the largest size for HD quality.
If IDM and 1DM app are not working the last option is to use screen recorder.