Welcome to the Forum, @Electrical-Engineer! 
That’s the way the Forum works for everyone. While you’re at Trust Level 0, you can’t upload an attachment aside from an image, but you can still post a link if you’ve uploaded the video elsewhere (e.g., YouTube). You can upload videos of 5.86 MB or less starting at Trust Level 1. Just spending some time reading other posts in the Forum can easily get you over the hump. Given the title of your topic, I’d suggest starting with some of these: