Look, one thing you have to accept, it's not SRKians who started saying this. It was international media. It's not some big conspiracy to undermine others, big websites and influential magazines said this on their own. Un ka kya faida SRK ko #1 kehne main?
Even India's media calls him the biggest, so it doesn't matter what haters say, this is what people think of him, get used to it.
Go to the street and start talking to someone about "King Khan", "Badshah of Bollywood", they will automatically assume that you are talking about SRK. Certain fanbases call their star "the real king", but if you have to put "real" before the "king", then he really isn't the king.
Fact is still today he makes more money than others, fact is even today he tops polls, fact is even today he gets excellent openings. Fact is no one is ready to write him off, fact is distributors are still paying huge amounts for his movies. Still top directors want to work with him, still top heroines want to work with him. Just look at his movie Raees this year. Maybe some people have forgotten, but the movie was facing issue after issue from political parties, a week before release we didn't know what was happening. Still he came with a mediocre movie and absolutely crushed the competition.
We don't need a video to tell us he is the biggest, even haters know it in their bones. That's why they get so riled up when he is talked about in such high regard.