Manfrotto 131DDB Tripod Accessory Arm for Four Heads (Black)

This item has multiple mounts for camera/tripod heads. You can attach as many as 4 heads but it does not come with the heads. If you click on the following link, you will see all the compatible heads; https://www.bhphotovideo.com/c/search?sortType=default&Ns=p_OVER_ALL_RATE%7c1&ci=140&fct=fct_head-type_1544%7cball-heads%2bfct_head-type_1544%7cgeared-heads%2bfct_head-type_1544%7cpan-tilt-heads%2bfct_head-type_1544%7cpistol-grip-heads&srtclk=sort&N=4075788769&

From the center of the center mount to the center of the end mount it can be up to around 16 inches.

Yes the Manfrotto 131DDB Tripod Accessory Arm for Four Heads (Black) comes with the two camera supports on top and one on each side as shown in the photos.

The Manfrotto 131DBB is compatible with tripods that have 3/8 threads.

Currently the price difference is not as broad as this. As to why there is a any difference in price, we would go with the explanation the chrome plating costs more. Also know that retail pricing is not linear. It is based on cost, supply and demand. Those factors are what determine price. A much cheaper price might reflect too much inventory and the product must be moved. A high price might reflect short supply and high demand as well as manufacturing cost.

I have both the Arm and the Mac and would not trust it. Too much weight distributed on my ne connector

The befree supports 17lbs, so it should be ok.

As long as your camcorder has 3/8 -16 female tripod sockets to connect the camera to the Manfrotto 131DD Tripod Accessory Arm (or you will be using a tripod head on the threads to convert to the smaller 1/4 -20 threads, and as long as the tripod can support the weight of the arm and the camcorders you wish to connect to the arm, it should be compatible for your usage needs.