Poor quality in sharing video

Hello.

Since the Covid-19-panedmic, I have started an online quiz-thing. I usually make a PowerPoint-presentation, which I share through Screen Sharing. When the slides contain text, there is usually no problem. Audio (in certain music-questions) I send to the contestants by sharing a Google Tab, in which I play the mp3-file.

The problem arises when I try to send video-images. I tried sharing the video by sharing the Google tab where I play it in, but then the image quality isn’t very good. When I shared it through sharing my VLC-player, the quality remains bad.

My question is: in what way can I improve the quality of the video-images?

Oh, I use Jitsi Meet, the free online option for video conferencing.

Looking forward to your reactions,
Rob