I have seen those, look pretty fun. I would never consider using them to hold any kind of load though, especially because of how a hook is mean to perform (its not a platform, it is designed to rectify automatically with loads, so nothing can slip off). When you do use it in suspension I would recommend using a fail-safe mechanism, so if things go wrong and a load is placed on the hook it will detach form any rig. (don’t tell your victim though )
Anal hooks are not to be used to support any weight at all. They are good for impaling someone who is already suspended by other means, especially if the hook is fixed to a non-moving surface (wall, st. andrew's cross, etc) but they absolutely positively should not be hold any weight at all.
Use them as is described on the Extreme Restraints page - tied to collars, other bondage ropes, etc. But DO NOT use them to support ANY weight.
I bought one of those a few months ago; way cool fun.
As the lovely Etiole says, not for weight bearing, but good if you suspend your sub, then tie it in after the load is distributed. If you put any pressure on it when your sub can't pull away or marginally wiggle for some degree of comfort, you risk a wrecked rectum, sphincter puncture, butt blow-out, a total arse-tastrophy
I like to put her in high heals, then affix her to one of these that's hung from a beam, at such a height that she can't stand on her toes or one leg to lift herself off. Basically trapped with minimal contact and retaining total and frustrating use of her limbs. Delicious fun to hook her up like this and leave her on show when visitors arrive.
You don't want to go subsidising the incomes of any proctologists though.