The Grizzly and the Mako the one Hammerhead 'makes' are indeed the same.
The fabric name is: NBLUCK LK500 and it's not made by Hammerhead in Canada but by
Ningbo Luck Vehicle Co in ....... China
http://www.nbluck.com.cn/
There's another buggy that looks just like called the Renli but the quality isn't so good.
http://www.renlivehicle.cn/showproduct.asp?id=347
Looking at the pictures on the website from Hammerhead Canada I can see they first sold the Renli (calling it Mako) and then switched to the better NBLUCK (still calling it Mako).
And yes PAbuggy I too think the 450 looks really wide. I even think the wheelbase of the 450 is almost the same as the NBLUCK but the frame of the 450 looks much smaller.
In the video you see it hit the ground pretty easy.
From the info in the vid I understand it has a manual gearbox which I don't prefer.