Teachers and students are not hearing the audio when they play videos during a live Google Meet meeting. I recomend you provide students with the video prior to your meeting. Let them watch the video before your Google Meet meeting and then discuss the video during the meeting.
If you absolutely need to play a video during a Google Meet meeting, these two videos will show you how you can play and hear a video during a Google Meet meeting. Contact me or your area DLCs if you need additional support. Solution #2 is what you should try first if you are using a Windows computer.