Yes, it is better to use white dogs!
Regarding markmanship... it is clear in the video you can see awful shots. But if you hunted sometime wild boars, with hounds at a short distance behind them, you will appreciate they cross the "cortaderos" (the clear spaces) really fast, and without a lot of advice. You don´t know where they are going to cross, and generally you have one or two seconds to see what are you shooting and take the shot. The "cortaderos" in the video are WIDER than the normal ones. It is much more difficult shooting a boar in a "monteria" than in the driven hunts you can have in Romania and Hungary.
Regarding the survival of the hunters... well, it is customary before the dogs are released to see where the neighbouring hunters are, and agree the limits where you are or not going to shoot. Every year I think they are some casualties, but not as many as you imagine; and most of them are in "informal" hunts, where the hunters are carelessly placed.
I love this kind of driven hunt, but there are many rules you must know, most of them regarding safety, and you must stick to them... or you will never hunt again with the group.