Youtube videos are as high as 1080P but... it depends on the who made the video to decide resolution. If you click on the little gear in the lower right (the Settings icon) you can decide from the available choices.
"It's tough to make predictions, especially when it involves the future." ~Attributed to many
"In theory, there is no difference between theory and practice. But, in practice, there is." ~(perhaps by) Yogi Berra
"Those who have knowledge, don't predict. Those who predict, don't have knowledge."~ Lau tzu