That was quite interesting, but like Bugga said, an unbelievable amount of people claim to be Jagex mods all the time. I wouldn't buy this unless he was somehow able to verify or prove that he really was an ex-mod.
If he was legitimately a Jagex mod though, it would be very interesting to hear what he has to say about the inside of the company and about the direction the game is going. All it would take is 1 legitimate ex-mod to go public with the information about how corrupt and greedy the company really is, and about all the things that go on behind closed doors, and people would know the truth, and our suspicions would be confirmed haha.
Unfortunately, this is probably just some random guy seeking attention and trying to stain the name of the company by trying to contact Youtubers and get them to fall for his little stunt like this guy did.
EDIT: The video has been removed.