It does depend exactly what you need, but there are many ways to add video onto a Moodle page. There's no specific 'template supporting video' as videos are most often simply treated as another resource, like images, or text, in the main editor.
But, I couldn't find the exact position where I add these html and css. Where is the core page which you state in moodle directory structure?
Thanks in advance.
You said the front page but you talk about a custom login page.
If you want video on the front page, you can add one anywhere you can add text - topic box, labels, HTML blocks, etc.
If you mean the login page, you have to use CSS. You can add custom CSS to the core Moodle Themes (Boost and Classic) - for Boost, go to Site Admin > Appearance > Themes > Boost > Advanced Settings
Ps. Thanks for your PM but I don’t ever respond privately, mainly because the answer is not visible to anyone else.
Under appearance, under frontpage, we can choose image for header. Instead of image, we want to show video. And we want to add sone new buttons near login button on the header. Ok, I understand your suggestion. But, isn't it needed to use the header's id or name, where can I find this? From code? If I don't know, then, how can remove header and add video in its place?
But a much simpler way to add your video would be to do as Richard, Gareth and I have already suggested - use a label on the front page.
Because, all of you say can be done after logging and turning the edit on. However what I want is about login page and I can't show this page directly and turn on editing. I only change the settings from site admin-> appearance-> themes-> moove. And there is not an option as label text or something else. Only I can add either html or css from different locations, but for every page and I only want this for front page. Because there isn't a location for both using html, css and js, I can't hide also.
"Include a topic section -> This adds a topic section to the centre-top of the front page. When editing is turned on, resources and/or activities can be added to the topic section using the dropdown menus, in the same way as on a course page.", i.e. add a label just like you would on a course.