Update video sizing

...ations/0311_alter_districtarticlepage_content_and_more.py

...ons/migrations/0068_alter_electionsarticlepage_content.py

...migrations/0151_alter_mainarticlepage_content_and_more.py

shared/blocks/parents/video.py

...yleguide2/includes/atoms/youtube_video/youtube_video.html

...grations/0124_alter_uniwebarticlepage_content_and_more.py