YouTube Video Size on TV

I mainly play YouTube videos on the PS4. Recently though am using the Android Big Box 2 to play You tube videos. Using the same TV screen am noticing extremely noticeable Black bars for some videos which were previously not there when using the PS4. For example:

I know normally bars are due to screen ratio bla bla…

Does this mean the PS4 App handles screen ratio differently/better than the Playstore App…

And how does one make the Videos on the Android Box fill the screen, similar to the output with the PS4

Well,in my experience the Youtube app for android is really tailored so well to work with Android TV.I dont know if it works well with android boxes though…I also use Youtube on My PS4 and its been an awesome experience,much better than the Youtube App for Android TV on my Sony Bravia.