ratios de video e imágenes para poner como background: y background video
https://stackoverflow.com/questions/22874155/video-tag-to-fill-100-div-regardless-of-ratios
https://css-tricks.com/full-page-background-video-styles/
Posicionar css
https://developer.mozilla.org/es/docs/Web/CSS/object-fit
https://www.w3schools.com/css/css3_object-fit.asp
https://www.w3schools.com/cssref/css3_pr_object-position.asp
https://css-tricks.com/almanac/properties/o/object-fit/
https://css-tricks.com/almanac/properties/o/object-position/
Aspect-ratio:
https://maugelves.com/no-me-rompas-el-aspect-ratio-usa-el-object-fit/