This particular card-based user interface no doubt has the signature of a certain Matias Duarte, who previously used a card UI as he worked on webOS, and to see it arriving on the mobile YouTube website eventually does bring a glimmer of hope to the heart. For those who have recently made use of the YouTube app on Android or iOS, you would find that the website is rather similar.
This particular content will be split up into cards, where you would be able to enjoy both video and information as a single card, while there is also the comments card which is located at the bottom of the page. Not only that, the video thumbnails are also a wee a bit bigger in size, making the entire layout more pleasant.