It always amazes me how people get so offended at any slight they perceive against their country and then somehow think it's appropriate to rip apart a country that they do not know themselves. How is that any different? Or any more appropriate? 
So many people have commented because they felt that you were attacking Bulgaria and then they proceeded to attack the United States. They never stopped to actually read what you wrote (you DON'T LIKE the VIDEO but, you LOVE Sofia and BULGARIA) and instead just decided to rip on you and your country of origin?
How does that make them any more culturally competent or any way superior to you? It just shows that they are as ignorant and racist as they (very mistakenly) thought you were.