EDIT relevant snippet:

On PCs it is usually not difficult for people to navigate to any search engine. Google in fact makes this point virtually every time someone raises antitrust concerns about their practices. Their defense ignores the hugely important fact that there are many other important ways that search services compete. Search engines compete to index the Web as fully as possible so they can generate good search results, they compete to gain advertisers (the source of revenue in this business), and they compete to gain distribution of their search boxes through Web sites. Consumers will not benefit from clicking to alternative sites unless all search engines have a fair opportunity to compete in each of these areas.

Oh Microsoft, how I'd like for you to become even more irrelevant than you already are.

The actual accusation is that YouTube only allows Google to properly index their videos, giving Google Search an unfair advantage.

Consumers won't switch to a search engine that can't index everything they want, and Bing can't index YouTube properly if Google won't let them.

Consumers will not benefit at all, since these companies can't index as large a portion of the web as Google could alone.