operaoverseer: What you say would make sense if this were an old issue. It is not. This problem has only been going on for a very short time. I have been using Opera since it was a product one had to pay for. I have been using YouTube for many years. This is the very first time this problem has arisen.
So either YouTube has suddenly started doing something new and deleterious, or Opera is not handling memory usage the same as it used to. I have no way of knowing for sure, but I'll bet on the latter.