Can I lazy load a video?
As with image elements, you can also lazy-load video. Videos are commonly loaded with the <video> element (although an alternate method using <img> has emerged with limited implementation). How to lazy-load <video> depends on the use case, though.
How do you load an entire video when the webpage is loaded?
HTML | <video> preload Attribute
auto: It is used to specify that the browser should load the entire video when the page loads. metadata: It is used to specify that the browser should load only metadata when the page loads.