This is the reply I got from Primate98:

"If you're thinking that Israel used nukes, I would agree.

My thesis would be this: they located an underground Hamas ammunition depot and decided to take it out. As we are repeatedly told, Hamas has an elaborate tunnel system and obviously such facilities would be located underground and accessible through the tunnels. They destroyed it using two tactical nukes smuggled in to the locations. (From other research, I believe that they have a stash of about <50 5kT nuclear devices.)

If you examine the first video, there's no sound of a jet and no visible or audible incoming missile or bomb. From the second explosion, there's also no flash, very little fireball, and no shockwave or loud boom. From that, we can would conclude both of these detonated underground.

You can also observe the sound of many secondary explosions. That is some of the ordnance there "cooking off". We don't see any evidence of it because, again, it's all underground. The thick black smoke is from the incompletely burned hydrocarbons of explosives or rocket propellant.

In the second video, we can observe no crater or even an epicenter. The building shown right at the beginning doesn't even have surface damage from debris. The wreckage itself is reminiscent of 911, in that we can hardly identify what had been there, as we would be able to if something had either blown apart or collapsed. Rather, most of it was reduced to dust.

Interestingly, on the very heavily damaged building on the left side of the site, on the left side of that building you can see part of it down low was also dustified while the building next door shows no surface damage, and again next to unrecognizable wreckage. What sort of bomb creates that kind of pattern in the damage? No conventional one, of course."