www.wysiwygwebbuilder.com

If I insert a video from Youtube, when the pointer over the video, the scroll does not work. How can I fix this?

You cannot 'fix' this. The reason for this is that YouTube uses an Inline frame to play videos.
This is unrelated to WWB.

I found a solution that allows scrolling over the player. Found the solution here: https://jsfiddle.net/th0LxLbv/2/
When I installed the CSS code in WWB, the scrolling turned on, but the player behaves incorrectly and has problems with the flex grid. The player does not stretch properly.
https://snipboard.io/DBk4IS.jpg

I am not good at coding, so please help with the project. Demo of the project here:
https://drive.google.com/file/d/1VjeS0J ... sp=sharing

I'm sorry, I cannot help you with third party code.
But I am not sure why you need custom code, because the YouTube object is responsive by design
By adding custom code you will break this functionality.

Note that if you use a flexgrid then you will need to set the flexbox properyies of the element otherwise they will not scale.
However, this is unrelated to your original question.