searching a value in watch window

This is now natively supported in Visual Studio 2019

Searching for objects and properties in the Watch, Autos, and Locals Window by Leslie Richardson

I'm afraid there is no such built in search functionality in the VS2010 watch window (although the watch window has a lots of cool features).

See also this unresolved question: Searching for text in an Object watch window in visual studio

However there are some commercial extensions which offers that functionality.

E.g.: Excerpt from the OzCode VS extension feature list:

Search

When debugging objects and collections, you are often looking for a specific property or field, or a value held within a property or field. Unfortunately, this usually involves either a lot of clicking and scrolling, or writing custom debug-specific code. Finding items even in simple structures is not easy, not to mention doing so in a complex object graph. With our “Search” feature, this is no longer the case.

I like to use the Immediate window (Debug ==> Windows ==> Immediate) and LINQ to search data structures. E.g.:

queries.Find(q => q.Name.Equals("HTTP_Response_Splitting"))