There are many factors to take into account here.
First of all, these guys are genetic freaks when it comes to handling heavy loads. Some guys are more prone to spine injuries, and some are less prone. I am willing to bet these guys are structurally "made" for these lifts.
Secondly, you have to question form sometimes. These guys are lifting, and have been lifting for several years like this...and they are still doing it. They are doing something right. There ability to keep pushing the envelope speaks for itself in a sense.
Thirdly, they aren't really rounding their lumbar. Their thoracic, yes, but not the lumbar. The thoracic spine is naturally in a posteriorly convex curve, so it is designed to transfer load through it with that curve (to an extent). It is much worse to round the lumbar than the thoracic due to the comparative structure of the vertebral joints.
Fourthly, yes they are looking down. Again, you have to question what you think is proper form. Many power lifters say to look slightly down, especially on the deadlift. This works as a form cue, because you want to push up and away from where you are looking. It works for some, and not for others. I would not say looking down is bad form, it just depends on how your body compensates due to head/eye position. I actually began doing this several months ago, and it actually helps me keep better form.
5th, there are inherent risks in any top level competition. Whether it is holding a football while cutting around at top speeds grass field while three 250 lb men try to steamroll you, or playing a several 3 hour tennis matches in a week. These guys are compromising their well being for the glory of the sport and being the best.