Responsiveness of YouTube Videos in main content area
Examples on sites such as https://www.arch.cam.ac.uk/prospective-students/undergraduates have shown that YouTube videos are not properly responsive in the main content area of the page.
It does behave correctly on https://www.undergraduate.study.cam.ac.uk/courses - the implementation is different as Undergraduate is an old, heavily customised site. Need a solution for the vast majority of standard sites.