@Vin20 Sure, :p. So to watch any video online you need to download it to your computer, so technically every video can be downloaded. But it's important to know that you need to have access to the video.
The first method is the one I explained. Right Click anywhere near the video, Go to Inspect Element. Then by browsing with the mouse on the source code of the website you can find the link of the video (might be easier to understand with a video). When you find the link all you need is to open the link and download the video.
But a lot of websites have protection against that, so there is a second method. Basically you open the video, then Right Click - Inspect Element. On the tab that opens you click in Sources, then you find the video (it will have a video extension, like Mp4 or something). Then you right click and copy the link. After that you need to have VLC, go to Media - Convert/Save, then click in Network, there you paste the video URL, then you click Save, and then you wait. Yes it's a much more complicated method, but hopefully it's understandable.
Extensions basically do those processes for you, I never found an extension that does the second one, but if the ones suggested above work it'd easier to use them. Otherwise the second method should work.