You can present a particular Google Chrome Tab and only show the contents of that tab.  In addition, you can present a Google Chrome Tab that has video/audio that you are viewing on your screen (ex: Youtube video) to everyone in the Google Meet (at the same quality you are viewing it).  

Note:  When you record a Google Hangout Meet, you can now show a video within that recording. 

See the short 3-minute video below which demonstrates how this is done: 

https://drive.google.com/file/d/11nVyH0AYE3JWSirtYELjDPwFA-K-o_Ak/view