@Dhiraj - I connected my pendrive to the 3.0 port and it detects.
1. It showed all the files and played all formats - mkv, mp4. It also supports HEVC encoded files too.
2. It doesn't support high bitrate files, I tried playing a 7GB video file and it just loads. Also noticed while playing the media I can see the data streaming and being played parallelly. Also if the STB has no access to internet then media playback isn't possible on STB. So it's kind of like Plex where it uploads data to remote server and then streams the data, have to test it out more.
3. Also when you eject, add more files to the usb, the STB doesn't detect the new files unless you restart the STB.