Yisroel Dovid Weiss is a bit of a nutter. He's the leader of a splinter of Neturei Karta, a ulta-Orthodox group that opposes Zionism quite virulently. He's on the extreme fringe of that.

Incidentally, while the video doesn't work in the US, I'm somewhat surprised he'd deny the Holocaust--he's openly discussed it on multiple occasions, and some of his family died in it (at least according to him). His main talking points on it are that Zionism has used the Holocaust ideologically (which I don't think is historically accurate), but his argument is mostly religious and about Zionism, not the Holocaust.

This is heavily covered in the FAQ. Here's a link which lists some similar questions that have been asked on the subject if no one gives you a satisfactory answer here. Hope it helps.

http://www.reddit.com/r/AskHistorians/wiki/wwii#wiki_holocaust_denial

What exactly do Holocaust deniers claim never happened (I find it hard to imagine that they could deny WWII all together)?

This thread gives you a basic idea of what they claim, and where it comes from.

Basically, here's a breakdown:

• Deniers claim that the killings were not as numerous, nor genocidal, as they were.

• Some deniers claim it never really happened at all, that death camps are fabricated, etc.

• Jews weren't the target, Slavic people were.

• Jews wanted it to happen so that they could gain sympathy and thereby gain a nation-state of their own.

These are the ones I hear the most often. A breakdown on each one:

Deniers claim that the killings were not as numerous, nor genocidal, as they were.

While the actual number of killings is disputed by many sources, that doesn't mean it isn't horrific or genocidal. It is now very clear that even on the lower end of the estimates, 3 million Jews were killed. That number alone is huge. Consider that there were estimated to be 16 million Jews around the world in 1939, it's obvious what a significant impact this was. Even if there were 30 million Jews around, that would constitute the death of 10% of the population of a group around the world; a huge amount by any means.

Some deniers claim it never really happened at all, that death camps are fabricated, etc.

Given the excessive eyewitness accounts, the admissions of guilt and the consistently available pictures of survivors, I think it's safe to say that people who cling to this are the type to doubt the Earth being round if they don't see it with their own eyes. They don't even justify a response.

Jews weren't the target, Slavic people were.

There is a considerable number of Slavic peoples who were killed. Personally, I don't doubt that Slavs were also targets of the Nazis for genocide. However, one genocide doesn't mean another didn't happen. Wanting the extermination of two groups, especially when it's the Nazis we're talking about, is not surprising. This isn't some kind of "Oh, more Slavs were killed, Jews shouldn't complain" tally, and anyone making that comparison should be ashamed.

Jews wanted it to happen so that they could gain sympathy and thereby gain a nation-state of their own.

Typically this relies on quotes that had very little relation to the Holocaust, and a post hoc ergo propter hoc (after, therefore before) fallacy. People assume that because the Holocaust was used for the justification of Israel after it ended, that it must've been planned. The logic is faulty, there is nothing credible to suggest that Hitler worked with Jews, and Jews had already been promised a state of sorts by the British; they had no reason to seek some kind of sympathy just because there was deadlock. In fact, the idea of the Holocaust being planned would've HURT the attempts to establish the state of Israel; movement and immigration into Israel was the goal of the Zionist movement, because it was believed that self-determination within the territory by the Jewish state would lead to the establishment of Israel, not some kind of sympathy-garnering plan.