Install ClickToFlash. This will show you a large grey rectangle with any Flash content. Right clicking on that gives you the option of viewing H.264 on YouTube. This will likely avoid any Flash related problems.
No. You're not alone. I noticed it start to do that about a month ago. I tried both Safari and Firefox and suffered browser crashes. I'm very certain that the problem is at their end. Browser crashes caused by a web-site is a serious problem. The question I have is, how do we report it and who do we report it to?