If a corporation "moves" oversees to avoid taxes, they aren't allowed to reap the benefits of the country whose taxes they wished to avoid.
If a billionaire moves to avoid taxes, they and their assets are cut off from the system whose taxes they wished to avoid. Oh, you want to move overseas but keep your money in banking institutions propped up by the US government? Too bad. You want your corporations to keep the full protection of the US government (intellectual capital protection, copyright, etc...)? Too bad! You want your company to take full advantage of all the US has to offer (great education system, a large consumer base, secure capital markets, a relatively stable government)? Too bad!
Most of these folks are just greedy fucks who know how good they have it...but somehow they want more, yet expect that people with exponentially less wealth will pay for it. I don't like that.
Note - the government isn't always the best at allocating capital or resources...but neither are private citizens or corporations.
Now, granted, I don't know that I have ever seen it put forth that they were ideal levels or anything. I just have never heard the top end tax rate blamed for that. Biggest thing I have seen it blamed on would be employer tied insurance and the like.
His most important point though is that things will not get better until a sufficient mass of public political pressure is brought to bear on the issue.