In SilverStripe you can add Videos within the TinyMCE Editor by using the "Insert Media" Button. In the "From the Web" tab, you can paste a URL of a resource, such as a Video hosted on Vimeo, YouTube or other video portals.
Videos inserted this way have a fixed size though and don't integrate nicely into responsive layouts. With some JavaScript and CSS you can progressively enhance your videos to become responsive.