Simply, You can play music or video by say !pm url on chat! (ex: !pm https://www.youtube.com/)
or open Main Menu by pressing the F9 or say !pm on chat.
This is Main Menu.
Press Request Queue (Green button)
Submit Url to Entry Box and press Queue Request!
Yes, But It's Media Player optimized for Music Videos.
So, You can also use this to play video that not music.
Please try switching to Chromium Beta Branch.
To go on the Chromium Branch:
If You already administrator, also on Playmusic Pro too!
or there is 2 options:
And click target or submit SteamID to Entry Box and click enter.
Turn on Authorization for Playmusic Pro.