Type a general term in YouTube's search box, click on "Search" and then click on "Wonder wheel" to find some suggestions. As you click on the suggestions, YouTube shows the search results next to the wheel and it lets you go back to the initial search terms.
"The Wonder wheel visually presents connections between related searches and your search term as an interactive diagram. Click the different nodes in the diagram to see how searches can branch out," explains Google.
While the idea seems interesting, I didn't find the "wonder wheel" very useful. It only works for some searches and the suggestions aren't diverse enough.