The whole screen or just the video?
Maybe post a link to one of the videos
My new iPad is just 5 months old ...when I am using you tube to watch programmes at times it goes out of focus ....this happens quite often with various programmes on you tube ...can anybody advice what could be the problem.?
You can crop a section of the image in the photos app on your ipad or resize it in one of many apps.
However, as it's just the video the problem is the quality/speed of the Internet connection.
YouTube streams scale dynamically dropping the quality down depending on the bandwidth and quality of the connection.