i want to do photography and take video at the same time using 2 different cameras.

i saw a guy that has this gadget, it was like an L frame. he can shoot with his dslr camera while a video cam is attached to the same frame. i've seen some straight bars where you can put the 2 cams on either side, but this worries me as i am using quite a heavy lens. and some of the reviews of these type of gadgets (eg. multi mount 6) always points this problem with heavy cams.

my question is, is there a similar gadget where you can put the primary cam on near if not the center of the bracket, so that the weight is properly supported?